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Bihar Board 12th Physics Model Papers

Bihar Board 12th Physics Model Question Paper 3 in English Medium

Instructions for the candidates :

1. Candidates are required to give answers in their own words as far as practicable.
2. Figures in the Right-hand margin indicates full marks.
3. While answering the questions, candidates should adhere to the words limit as far as practicable.
4. 15 Minutes of extra time has been allotted to read the questions carefully.
5. This question paper is divided into two sections : Section -A and Section-B
6. In Section A there are 35 Objective type questions which are compulsory, each carrying 1 mark. Darken the circle with Blue/Black ball pen against the correct option on OMR Sheet provided to you. Do not use Whitener/Liquid/ Blade/Nail on OMR Sheet, otherwise, your result will be treated as invalid.
7. In section-B, there are 18 Short answer type questions (each carrying 2 marks), out of which only 10 (ten) questions are to be answered Apart from this there are 06 Long Answer type questions each carrying 5 marks, out of which 3 questions are to be answered.
8. Use of any electronic device is prohibited.

Time : 3 Hours 15 Minute
Total Marks : 70

Objective Type Questions

There are 1 to 35 objective type questions with 4 options. Choose the correct option which is to be answered on OMR Sheet. (35 x 1 = 35)

Question 1.
Torque acting on dipole in electric field E is
\((a) \overrightarrow{\mathrm{p}} \times \overrightarrow{\mathrm{E}}
(b) \overrightarrow{\mathrm{P}} \cdot \overrightarrow{\mathrm{E}}
(c) \overrightarrow{\mathrm{E}} \times \overrightarrow{\mathrm{P}}
(d) P/E\)
Answer:
\((a) \overrightarrow{\mathrm{p}} \times \overrightarrow{\mathrm{E}}\)

Question 2.
The algebraic sum of currents meeting at a point in the electric circuit becomes
(a) Infinity
(b) Positive
(c) Zero
(d) Negative
Answer:
(c) Zero

Question 3.
The density of metal is d and sp. resistance is r. It is in the form of wire whose length is 1 and resistance is R. The resistance mass of metal should be

Answer:
(a)

Question 4.
The emf of cell is measured by
(a) Voltmeter
(b) Ammeter
(c) Galvanometer
(d) Potentiometer
Answer:
(d) Potentiometer

Question 5.
The balancing point is obtained in potentiometer by increasing the length of wire
(a) On minimum length
(b) On maximum length
(c) On the same length
(d) Indefinite
Answer:
(b) On maximum length

Question 6.
If two cells of E₁ and E₂ are balanced at length l₁ and l₂ in potentiometer wire then

Answer:
(b)

Question 7.
The phase difference between current and emf in the condition of resonance is
(a) π/2
(b) π/4
(c) π
(d) zero
Answer:
(d) zero

Question 8.
A copper ring lies in horizontal place. A bar magnet lies along its axis above the ring. The bar magnet is now released then
(a) Acceleration of the bar will be ‘g’
(b) Copper ring will go an cooling
(c) The acceleration of bar will be less than g
(d) The velocity of the bar will become upward
Answer:
(a) Acceleration of the bar will be ‘g’

Question 9.
The induced emf of rod is
(a) BLV
(b) B²L²V
(c) Zero
(d) None of these
Answer:
(c) Zero

Question 10.
The energy due to flow of current I in inductance L is
\((a) Zero
(b) \frac{1}{2} \mathrm{LI}^{2}
(c) \frac{1}{2} \mathrm{LI}
(d) \frac{1}{2} \mathrm{L}^{2} \mathrm{I}^{2}\)
(a) Zero
Answer:
\((b) \frac{1}{2} \mathrm{LI}^{2}\)

Question 11.
The power loss in A.C. circuit is
(a) only resistance
(b) only capacity
(c) only inductance
(d) All of these
Answer:
(a) only resistance

Question 12.
The unit of mutualinductance is
(a) Weber
(b) Ohm
(c) Henry
(d) Gauss
Answer:
(c) Henry

Question 13.
If the real and apparent power of A.C. circuit is PT and PA respectively then power factor is
\((a) \frac{P_{T}}{P_{A}}
(b) \mathrm{P}_{\mathrm{T}} \times \mathrm{P}_{\mathrm{A}}
(c) \frac{\mathrm{P}_{\mathrm{A}}}{\mathrm{P}_{\mathrm{T}}}
(d) \mathrm{P}_{\mathrm{A}}+\mathrm{P}_{\mathrm{T}}$\)
Answer:
\((a) \frac{P_{T}}{P_{A}}\)

Question 14.
Which have minimum wave length in the following?
(a) x-ray
(b) y-ray
(c) Micro wave
(d) Radio-wave
Answer:
(b) y-ray

Question 15.
A Thin prism \(\left(\mu=\frac{3}{2}\right)\) in air is immersed in water \(\left(\mu=\frac{6}{4}\right)\). The ratio of angle of deviation in both condition will be
\((a) \frac{15}{8}
(b) \frac{8}{15}
(c) \frac{5}{2}
(d) \frac{2}{5}\)
Answer:
\((c) \frac{5}{2}\)

Question 16.
The refractive index of material of prism is ^3 • The minimum deviation for this prism is :
(a) 30°
(b) 37°
(c) 45°
(d) 60°
Answer:
(d) 60°

Question 17.
The cause of coloured thin film is
(a) Scattering
(b) Interference
(c) Dispersion
(d) Diffraction
Answer:
(b) Interference

Question 18.
The radius of curvature of double convex lens is 20cm and μ = 1.5 then its power is
(a) 5D
(b) 10D
(c) 25D
(d) 20D
Answer:
(a) 5D

Question 19.
The vertical section of cornea is not symmetrical about their axis. The defects of vision in eye is called
(a) Short sightedness
(b) Hypermetropia
(c) Presbyopia
(d) Astigmatism
Answer:
(c) Presbyopia

Question 20.
The radius of curvature of plane mirror is
(a) Infinity
(b) Zero
(c) +5 cm
(d) -5 cm
Answer:
(a) Infinity

Question 21.
The ratio of intensity of two waves is 9:1 produces interference. The ratio of maximum and minimum intensity will be
(a) 10 : 8
(b) 9 : 1
(c) 4 : 1
(d) 2 : 1
Answer:
(c) 4 : 1

Question 22.
If the frequency of photon incident on the metallic surface becomes double then maximum kinetic energy of emitted electrons will be
(a) double
(b) more than double
(c) not change
(d) none of these
Answer:
(b) more than double

Question 23.
The photo electric effect supports
(a) Wave nature of light
(b) Particle nature of light
(c) Dual nature of light
(d) None of these
Answer:
(a) Wave nature of light

Question 24.
The electron in hydrogen atom comes from third orbit to second orbit, then released energy is
(a) 1.5 leV
(b) 3.4 eV
(c) 1.89 eV
(d) 0.54 eV
Answer:
(c) 1.89 eV

Question 25.
The angular momentum of electron in hydrogen atom in lowest energy level is
\((a) \frac{h}{\pi}
(b) \frac{h}{2 \pi}
(c) \frac{2 \pi}{h}
(d) \frac{\pi}{h}\)
Answer:
\((b) \frac{h}{2 \pi}\)

Question 26.
In nuclear reactor the controlling rods are made up
(a) of Cadmium
(b) of Uranium
(c) of Graphite
(d) of Plutonium
Answer:
(a) of Cadmium

Question 27.
Which is unstable?
(a) neutron
(b) proton
(c) electron
(d) α-particle
Answer:
(a) neutron

Question 28.
The Boolean expression of NOR gate is
(a) A + B = y
(b) \(\overline{\mathrm{A.B}}=y\)
(c) A.B = y
(d) \(\overline{\mathrm{A+B}}=y\)
Answer:
\((d) [latex]\overline{\mathrm{A+B}}=y\)

Question 29.
In figure logic gate is

(a) OR
(b) NOR
(c) NAND
(d) AND
Answer:
(d) AND

Question 30.
The majority current carrier in p-type semiconductor is
(a) electron
(b) hole
(c) photon
(d) proton
Answer:
(b) hole

Question 31.
The semi conductor behaves at absolute temperature
(a) fully conductor
(b) fully insulator
(c) super conductor
(d) semi conductor
Answer:
(b) fully insulator

Question 32.
The conduction band are empty in
(a) Insulator
(b) Semi conductor
(c) In metal
(d) None of these
Answer:
(b) Semi conductor

Question 33.
Which is not the example of digital communications?
(a) E-mail
(b) Cellular phone
(c) Television
(d) Communication satellite
Answer:
(c) Television

Question 34.
The value of amplitude modulation index is
(a) Always zero
(b) between 1 and
(c) Between 0 and 1
(d) Always infinity
Answer:
(c) Between 0 and 1

Question 35.
The relation between a and P in transistor is

Answer:
(b)

Non-Objective Type Questions
Short Answer Type Questions-

Q.No. 1 to 18 are short answers type question. Each question carries 2 marks. Answer any ten (10) question.

Question 1.
What is Electrostatic shielding?
Answer:
The electrostatic shielding is the best way to protect some area in vaccum from the influence of external electric field. ,
The technique of electrostatic shielding is applied basically in designing the cable for television.

Question 2.
What is polar and non polar dielectrics?
Answer:
Non-Polar dielectric :
A dielectric, in the atom or molecule of which, the centre of gravity of positive and negative charge coincide is called non-polar dielectric. Due to zero separation between +ve and -ve charges the electric dipole moment of such atom or molecules is zero.

Polar dielectric :
A dielectric, in the atom or molecules of which the centre of gravity of +ve and -ve charge do not coincide, is called polar dielectric

eg-NH₃, HC1, H₂O, CO₂ etc.

Due to finite separation +ve and -ve charges, such atoms or molecules possess a finite electric dipole moment.

Question 3.
What is current density? Write its S.I. unit and dimension.
Answer:
Current per unit area is called current density. It is denoted by ‘J’
\(\mathrm{J}=\frac{1}{\mathrm{A}}\)

It is a vector quantity
S.I. unit : Ampere/m²
Dimension : [M°L^-2 T°]

Question 4.
Write two factors on which resistivity of conductor depends.
Answer:
The resistivity of conductor depends upon following factors :

• It depends upon temperature,
• It depends upon nature of substance of conductor.

Question 5.
Calculate the value of I in given circuit.

Answer:
According to figure
R₁ and R₂ are in series
R_s = R₁ + R₂
R_s = 30 + 30 = 60Ω
Now, R₃ and R_s are in parallel

Question 6.
Write Lenz’s law for electromagnetic induction.
Answer:
Lenz’s law: This law states that whenever electric current is produced in circuit or in coil due to electromagnetic induction then it opposes that causes due to which it is produced.
\(\mathrm{e}=-\mathrm{n} \frac{\mathrm{d} \phi}{\mathrm{dt}}\)
e = induced emf

This law obeys the principle of Conservation of Energy.

Question 7.
Write two applications of ultraviolet waves.
Answer:

• They are used to preserve food stuff and make drinking water free from bacteria, as these rays can kill bacteria, germs etc.
• They are used for sterlizing surgical instruments.

Question 8.
The power of two lens are 12 D and -2D are kept in contact. What is the focal length of combination.?
Answer:
Power of combination P = P₁ + P₂
P = 12 – 2 = 10
Focal length of combination
\(f=\frac{1}{p}=\frac{1}{10} \times 100=10 \mathrm{cm} ; f=10 \mathrm{cm}\)

Question 9.
Write Brewter’s law.
Answer:
This law states that when the unpolarised light is incident on the surface on polarising angle then refractive index of medium is equal to tangent of polarising angle.
\(\mu=\tan i_{p}\)

Question 10.
State properties of photon.
Answer:
Properties of photon are as follows :

• A photon travels with a speed of light in vacuum.
• A photon has zero rest mass.

Question 11.
State two uses of photo diode.
Answer:

• They are used as photo detectors to detect intensity of radiation.
• They are used as light operated switches.

Question 12.
What is Binding Energy per nucleon?
Answer:

• The binding energy per nucleon of a nucleus is the binding energy divided by the total number of nucleons.

B.E./Nucleon =
\(\frac{\Delta m \times 931 \mathrm{ev}}{\Delta}\)

Question 13.
What are limitations of amplitude modulation?
Answer:

• The quality of audio signal is not good,
• The atmospheric and industrial noise affect the audio signal,
• The efficiency of amplitude modulation is low.

Question 14.
Write the differences between N-type and P- type semi-conductor.
Answer:
N-type :

• when pentavalent impurity atom like As, Sb etc. are added in the intrinsic semi-conductor we get N- type of semi-conductor.
• The majority carriers in the N-type semi-conductor are electrons and minority carriers are hole.
• n_e >> n₀

P-type:

• When invalent impurity atoms like Gallium, Indium etc. are added in the intrinsic semi-condcutor we get p-type of semi conductors.
• The majority carriers in P-type semiconductor are holes and minority carriers are electrons.
• n_h >>n_e

Question 15.
What are base band and band width?
Answer:
Base Band:
In telecommunication and signal processing it describes channel and system what range of frequency is measured from zero Hz to cut off frequency.

Band Width :
It refers to the frequency range our which as equipotent rates on the portion of spectrum occupied by the signal.

Question 16.
Define Electric Intensity. Write its S.I. unit and dimension.
Answer:
Electric Intensity :
The electric intensity at a point in the electric field is defined as the force which is experienced by unit positive charge placed at the point. It is denoted by \(\vec{E}\)
\(\vec{E}=\frac{\vec{F}}{q_{0}}\)

S.I. unit : Newton/Coulomb
or
Volt/metre
Dimension : [MLT³I^-1]

Question 17.
Write properties of electric lines of force.
Answer:

• The electric lines of force originated from positive charge and terminate on negative charge.
• The electric lines of force never intersect to each other.

Question 18.
Why internal resistance of secondary cell is low?
Answer:
As in secondry cell, distance between two plates is greater and their size are big. There is no polarisation in secondary cell. Due to this, internal resistance of secondary¬cell is 10w.

Long Answer Type Questions

Q.No. 19 to 24 are long answers type question. Each question of this category carries 5 marks. Answer any three (3) question. (3 x 5 = 15)

Question 19.
State and Prove Gauss’s Theorem in electrostatics.
Answer:
Statement of Gauss’s Theorem : The net- outward normal electric flux through any closed surface of any shape is equal to l/ε₀ times the total charge contained within that surface i.e.

where indicates the surface integral over the whole

of the closed surface. Σ_q is the algebraic sum of all the charges (i.e. net charge in Coulombs) enclosed by surface S.

Proof of Gauss’s Theorem :
Let a point charge + q coulomb be placed at O within the closed surface. Let E be the electric field strength at P. Let OP=r and the permitivity of free space or vacuum be e0.

Consider a small area’ \(\overrightarrow{d S}\) of the surface surrounding the point P. Then the electric flux through \(\overrightarrow{d S}\) is given by

subtended by area dS at point O. Here 0 is the angle between \(\overrightarrow{d S}\) and \(\overrightarrow{E}\)

Hence electric flux through whole of the closed surface.
\(\phi=\oint_{S} \overrightarrow{\mathrm{E}} \cdot \overrightarrow{\mathrm{dS}}=\frac{q}{4 \pi \varepsilon_{0}} \times \oint d \Omega\)

But \(\oint d \Omega\) is the solid angle due to the entire closed surface S at an internal point O = 4π
∴ \( \quad \phi=\frac{q}{4 \pi \varepsilon_{0}} \cdot 4 \pi=\frac{1}{\varepsilon_{0}} q\)

It there are several charges, + q₁, + q₂, + q₃ + q₁ – q₂ – q₃ ………… inside the closed surface, each will contribute to the total electric flux. For positive charges the flux will be outward and hence positive; for negative charges the flux will be inward and negative. Therefore, the total electric flux in such a case

where Zq is the algebraic sum of the charges within the closed surface.

Hence total electric flux through any closed surface is equal to l/e0 times the total charge (in Coulomb) enclosed within the surface which is Gauss’s law.

Question 20.
Find an expression for the capacitance of a parallel plate capacitor when a dielectric slab of dielectric constant K and thickness \(t=\frac{d}{2}\) but of same area on the plates is inserted between the capacitor plate. (d = separation between the plates).
Answer:
Consider a paralled plate capacitor, area of each plate being A, the separation between the plates being d. Let a dielectric slab of dielectric constant K and thickness t < d be placed between the plates. The thickness of air between the plates is (d – t). If charges on plates are + Q and -Q, then surface charge density

The electric field between the plates in air,
\(\mathrm{E}_{1}=\frac{\sigma}{\varepsilon_{0}}=\frac{Q}{\varepsilon_{0} \mathrm{A}}\)

The electric field between the plates in slab,
\(\mathrm{E}_{2}=\frac{\sigma}{\mathrm{K} \varepsilon_{0}}=\frac{Q}{\mathrm{K} \varepsilon_{0} \mathrm{A}}\)

∴ The potential difference between the plates VAB = work done in carrying unit positive charge from one plate to another
= Σex (as field between the plates is not constant).

∴ Capacitance of capacitor.

Question 21.
State Biot-Savart law, giving the mathematical expression for it.
Use this law to derive the expression for the magnetic field due to a circular coil carrying current at a point along it axis.
How does a circular loop carrying current behave as a magnet?
Answer:
(i) Magnetic field at the axis of a circular loop : Consider a circular loop of radius R carrying current I, with its plane perpendicular to the plane of paper. Let P be a point of observation on the axis of this circular loop at a distance x from its centre O. Consider a small element of length dl of the coil at point A. The magnitude of the magnetic induction \(\overrightarrow{\mathrm{dB}}\) at point P due to this element is given by

The direction of \(\overrightarrow{\mathrm{dB}}\) is perpendicular to the plane containing \(\overrightarrow{\mathrm{dl}}\) and \(\overrightarrow{\mathrm{r}}\) is given by right hand screw rule. As the angle between \(\overrightarrow{\mathrm{dl}}\) and \(\overrightarrow{\mathrm{r}}\) is 90°, the magnitude of the magnetic induction \(\overrightarrow{\mathrm{dB}}\) is given by,
\(\overrightarrow{\theta B}=\frac{\mu_{0} t}{4 \pi} \frac{d \sin 9 \sigma^{0}}{r^{2}}=\frac{\mu_{0} d t^{2}}{4 \pi^{2}}\) …….(ii)

If we consider the magnetic induction produced by the whole of the circular coil, then by symmetry the components of magnetic induction perpendicular, to the axis will be cancelled out, while those parallel to the axis will be added up. Thus the resultant magnetic induction \(\overrightarrow{\mathrm{B}}\) at axial point P is along the axis and may be evaluated as follows :

The component of \(\overrightarrow{\mathrm{dB}}\) along the axis,

Therefore the magnitude of resultant magnetic induction at axial point P due to the whole circular coil is given by

Question 22.
Derive an expression for the force per unit length between two long straight parallel current carrying conductors. Hence define S.I. unit of current (ampere).
Answer:
Suppose two long thin straight conductors (or wires) PQ and RS are placed parallel to each other in vacuum (or air) carrying currents I₁ and I₂ respectively. It has been observed experimentally that when the current in the wire are in the same direction, they experience an attractive force (fig. a) and when they carry currents in opposite directions, they experience a repulsive force (fig. b). Let the conductors PQ and RS carry currents I₁ and I₂ in same direction and placed at separation r. (fig). Consider a current-element ‘ab’ of length AL of wire RS. The magnetic field produced by current-carrying conductor PQ at the location of other wire RS.

\(\mathrm{B}_{1}=\frac{\mu_{0} \mathrm{l}_{1}}{2 \pi r}\) ……………………… (i)

According to Maxwell’s right hand rule or right hand palm rule no. I, the direction of B l will be perpendicular to the plane of paper and directed downward. Due to this magnetic field, each element of other wire experiences a force. The direction of current element is perpendicular to the magnetic field; therefore the magnetic force on element ab of length ΔL.
\(\Delta F=\mathrm{B}_{x} \mathrm{I}_{2} \Delta \mathrm{L} \sin 90^{\circ}=\frac{\mu_{0} \mathrm{I}_{1}}{2 \pi r} \mathrm{I}_{2} \Delta \mathrm{L}\)

∴ The total force on conductor of length L will be
\(\mathrm{F}=\frac{\mu_{0} \mathrm{I}_{1} \mathrm{I}_{2}}{2 \pi r} \Sigma \Delta \mathrm{L}=\frac{\mu_{0} \mathrm{I}_{1} \mathrm{I}_{2}}{2 \pi r} \mathrm{L}\)

∴ Force acting on per unit length of conductor
\(f=\frac{F}{L}=\frac{\mu_{0} I_{1} I_{2}}{2 \pi r} N / m\)

According to Flemming’s left hand rule, the direction of magnetic force will be towards PQ i.e., the force will be attractive.

On the other hand if the currents I₁ and I₂ in wires are in opposite directions, the force will be repulsive. The magnitude of force in each case remains the same.

Definition of S.I. unit of Current (ampere):
In S.I. system of fundamental unit of current ‘ampere’ has been define assuming the force between the two currents carrying wires as standard.

The force between two parallel currents carrying conductors of separation r is

Thus I ampere is the current which when flowing in each of parallel conductors placed at separation I m in vacuum exert a force of 2 x 10^-7 on 1 m length of either wire.

Question 23.
With the help of a ray diagram, show the formation of image of a point object by refraction of light at a spherical surface separating two media of refractive indices n₁ and n₂ (n₂ > n₁), respectively. Using this diagram, derive the relation \(\frac{n_{2}}{v}-\frac{n_{1}}{u}=\frac{n_{1}-n_{1}}{R}\)

Write the sign conventions used. What happens to the focal length of convex lens when it is immersed in water?
Answer:
Formula for Refraction at Spherical Surface Concave Spherical Surface :
Let SPS’ be a spherical refracting surface, which separates media ‘1’ and ‘2’. Medium ‘ 1’ is rarer and medium ‘2’ is denser. The refractive indices of media ‘1’ and ‘2’ are n₁ and n₂ respectively (n₁ < n₂). Let P be the pole and C the centre of curvature and PC the principal axis of spherical refracting surface.

O is a point-object on the principal axis. An incident ray OA, after refraction at A on the spherical surface bends towards the normal OAN and moves along AB. Another incident ray OP falls on the surface normally and hence passes undeviated after refraction. These two rays, when produced backward meet at point I on principal axis. Thus I is the virtual image of O.

Let angle of incidence of ray OA be / and angle of refraction be r i.e.

If point A is very near to P, then angles i, r, a, P, Y will be very small, therefore sin i = i and sin r = r
From equation (iii)
\(\frac{i}{r}=\frac{n_{2}}{n_{1}}\)
Substituting values of i and r from (i) and (ii) we get
\(\frac{\gamma-\alpha}{\gamma-\beta}=\frac{n_{2}}{n_{1}} \text { or } n_{1}(\gamma-\alpha)=n_{2}(\gamma-\beta) \quad \ldots \text { (iv) }\)

The length of perpendicular AM dropped from A on the principal axis is h, i.e. AM = h. As angles a, P and y are very small, therefore
tana = α, tan β = β, tan γ = γ
Substituting these values in equation (iv)
n1 (tanY-tanoO = /j2(tanY-tanP) ……………. (v)
As point A is very close to P, point M is coincident with F

Let u, v and R be the distance of object O, image I and centre of curvature C from pole P. By sign convention PO, PI and PC are negative i.e. u = – PO, v = – PI and R = – PC

Substituting these values in (vii) we get

Question 24.
Derive Einstein’s photoelectric equation ^
\(\frac{1}{2}\)
\(m v^{2}=h v-h v_{0}\)
Answer:
Einstein’s Explanation of Photoelectric Effect: Einstein’s Photoelectric Equation :

Einstein explained photoelectric effect on the basis of quantum theory.

The main points are :

1. Light is propagated in the form of bundles of energy. Each bundle of erergy is called a quantum or photon and has energy hv, where h = Plank’s constant and v = frequency of light.

2. The photoelectric effect is due to collision of a photon of incident metal light and a bound electron of the metallic cathode.

3. When a photon of incident light falls on the metallic surface, it is completely absorbed. Before being absorbed it penetrates through a distance of nearly 10-8 m (or 100 A). The absorbed photon transfers its whole energy to a single electron. The energy of photon goes in two parts : a part of energy is used in releasing the electron from the metal surface (i.e., in overcoming work function) and the remaining part appears in the form of kinetic energy of the same electron.

If v be the frequency of incident light, the energy of photon = hv. If W be the work function of metal and Ek the maximum kinetic energy of photoelectron, then according to Einstein’s explanation.

hv = W + EK
or, EK = hv – W …………………….(i)

This is called Einstein’s photoelectric equation.

If v₀ be the threshold frequency, then if frequency of incident light is less then v0, no electron will be emitted and if the frequency of incident light be v0, then E_k = 0; so from equation (i)
0 = hv₀ – W or W = hv₀

If λ₀ be the threshold wavelength, then \(v_{0}=\frac{c}{\lambda_{0}}\), where c is the speed of light in vacuum.

∴ Work function
\(\mathrm{W}=h v_{0}=\frac{h c}{\lambda_{0}}\) ………………… (ii) Substituting this value in equation (i), we get
E_k = hv – hv₀ ……………….(iii)
This is another form of Einstein’s photoelectric equation.

Bihar Board 12th Biology Objective Questions and Answers

Bihar Board 12th Biology Objective Answers Chapter 2 Sexual Reproduction in Flowering Plants

Question 1.
Science of cultivation, breeding, marketing and arrangement of flowers is called
(a) arboriculture
(b) floriculture
(c) horticulture
(d) anthology
Answer:
(b) floriculture

Question 2.
Nonessential floral organs in a flower are
(a) sepals and petals
(b) anther and ovary
(c) stigma and filament
(d) petals only.
Answer:
(a) sepals and petals

Question 3.
The stamens represent
(a) microsporangia
(b) male gametophyte
(c) male gametes
(d) microsporophylls.
Answer:
(d) microsporophylls

Question 4.
Anther is generally
(a) monosporangiate
(b) bisporangiate
(c) letrasporangiate
(d) trisporangiate.
Answer:
(c) letrasporangiate

Question 5.
The anther wall consists of four wall layers where
(a) tapetum lies just inner to endothecium
(b) middle layers lie between endothecium and tapetum
(c) endothecium lies inner to middle layers
(d) tapetum lies next to epidermis.
Answer:
(b) middle layers lie between endothecium and tapetum

Question 6.
The innermost layer of anther is tapetum whose function is
(a) dehiscence
(b) mechanical
(c) nutrition
(d) protection.
Answer:
(c) nutrition

Question 7.
Callase enzyme which dissolves callose of pollen tetrads to separate four pollens is provided by
(a) pollens
(b) tapetum
(c) middle layers
(d) endothecium.
Answer:
(b) tapetum

Question 8.
In angiosperms various stages of reductional division can best be studied in
(a) young anthers
(b) mature anthers
(c) young ovules
(d) endosperm cells.
Answer:
(a) young anthers

Question 9.
Study of pollen grains is called
(a) micrology
(b) anthology
(c) palynology
(d) pomology
Answer:
(c) palynology

Question 10.
Several pollen grains form a unit designated as pollinium in Family
(a) Asteraceae
(c) Asclepiadaceae Pollen
(b) Cucurbitaceae
(d) Brassicaceae
Answer:
(c) Asclepiadaceae Pollen

Question 11.
Pollen grain is a
(a) megaspore
(b) microspore
(b) microspore
(d) microsporangium.
Answer:
(b) microspore

Question 12.
How many pollen mother cells should undergo meiotic division to produce 64 pollen grains ?
(a) 64
(b) 32
(c) 16
(d) 8
Answer:
(c) 16

Question 13.
How many meiotic divisions are required for the formation of 100 pollen grains ?
(a) 100
(b) 50
(c) 25
(d) 26
Answer:
(c) 25

Question 14.
One of the most resistant biological material present in the exine of pollen grain is
(a) pectocellulose
(b) sporopollenin
(c) suberin
(d) cellulose.
Answer:
(b) sporopollenin

Question 15.
What is the function of germ pore ?
(a) Emergence of radicle
(b) Absorption of water for seed germination
(c) Initiation of pollen tube
(d) All of these .
Answer:
(c) Initiation of pollen tube

Question 16.
_______of the pollen grain divides to form two male gametes.
(a) Vegetative cell
(b) Generative cell
(c) Microspore mother cell
(d) None of these
Answer:
(b) Generative cell

Question 17.
The three cells found in a pollen grain when it is shed at 3-celled stage are
(a) 1 vegetative cell, 1 generative cell, 1 male gamete
(b) 1 vegetative cell, 2 male gametes
(c) 1 generative cell, 2 male gametes
(d) either (a) or (b).
Answer:
(b) 1 vegetative cell, 2 male gametes

Question 18.
Megasporangium along with its protective integuments is called
(a) ovary
(b) ovule
(c) funicle
(d) chalaza
Answer:
(b) ovule

Question 19.
Mature ovules are classified on the basis of funiculus. If micropyle comes to lie close to the funiculus the ovule is termed as
(a) orthotropous
(b) anatropous
(c) hemitropous
(d) campylotropous
Answer:
(b) anatropous

Question 20.
When micropyle, chalaza and hilum lie in a straight line, the ovule is said to be
(a) anatropous
(b) orthotropous
(c) amphitropous
(d) campylotropous.
Answer:
(b) orthotropous

Question 21.
What is the function of filiform apparatus in an angiospermic embryo sac?
(a) Brings about opening of the pollen tube
(b) Guides the pollen tube into a synergid
(c) Prevents entry of more than one pollen tube into a synergid
(d) None of these
Answer:
(b) Guides the pollen tube into a synergid

Question 22.
The female gametophyte of a typical dicot at the time of fertilisation is
(a) 8 – celled
(b) 7 – celled
(c) 6 – celled
(d) 5 – celled
Answer:
(b) 7 – celled

Question 23.
Polygonum type of embryo sac is
(a) 8 – nucleate, 7 – celled
(b) 8 – nucleate, 8 – celled
(c) 7 – nucleate, 7 – celled
(d) 4 – nucleate, 3 – celled
Answer:
(a) 8 – nucleate, 7 – celled

Question 24.
Both chasmogamous and cleistogamous flowers are present in
(a) Helianthus
(b) Commelina
(c) Rosa
(d) Gossypium
Answer:
(b) Commelina

Question 25.
Even in absence of pollinating agents seed-setting is assured in
(a) Commelina
(b) Zostera
(c) Salvia
(d) Fig
Answer:
(a) Commelina

Question 26.
Male and female flowers are present on different plants (dioecious) to ensure xenogamy, in
(a) papaya
(b) bottle gourd
(c) maize
(d) all of these.
Answer:
(a) papaya

Question 27.
Feathery stigma occurs in
(a) pea
(b) wheat
(c) Datura
(d) Caesalpinia
Answer:
(b) wheat

Question 28.
Plants with ovaries having only one or a few ovules are generally pollinated by
(a) bees
(b) butterflies
(c) birds
(d) wind
Answer:
(d) wind

Question 29.
Which of the following is not a water pollinated plant ?
(a) Zostera
(b) Vallisneria
(c) Hydrilla
(d) Cannabis
Answer:
(d) Cannabis

Question 30.
Spiny or sticky pollen grains and large, attractively coloured flowers are associated with
(a) hydrophily
(b) entomophily
(c) ornithophily
(d) anemophily
Answer:
(b) entomophily

Question 31.
Fragrant flowers with well developed nectaries are an adaptation for
(a) hydrophily
(b) anemophily
(c) entomophily
(d) none of these
Answer:
(c) entomophily

Question 32.
Pollen kitt is generally found in
(a) anemophilous flowers
(b) entomophilous flowers
(c) ornithophilous flowers
(d) malacophilous flowers
Answer:
(b) entomophilous flowers

Question 33.
Which of these is a condition that makes flowers invariably autogamous ?
(a) Dioecy
(b) Self incompatibility
(c) Cleistogamy
(d) Xenogamy
Answer:
(c) Cleistogamy

Question 34.
Heterostyly as a contrivance for cross-pollination is found in
(a) Pennisetum
(b) Impatiens
(c) Primula vulgaris
(d) Oenothera
Answer:
(c) Primula vulgaris

Question 35.
The part of gynoecium that determines the compatible nature of pollen is
(a) stigma
(b) style
(c) ovary
(d) synergids
Answer:
(a) stigma

Question 36.
Part of the gynoecium which receives the pollen is called
(a) style
(b) stigma
(c) ovule
(d) ovary
Answer:
(b) stigma

Question 37.
Growth of pollen tube towards embryo sac is
(a) chemotropic
(b) thigmotaxis
(c) geotropic
(d) none of these
Answer:
(a) chemotropic

Question 38.
During the process of fertilisation the pollen tube of the pollen grain usually enters the embryo sac through
(a) integument
(b) nucellus
(c) chalaza
(d) micropyle
Answer:
(d) micropyle

Question 39.
Fusion of one of the male gametes with egg nucleus is referred to as
(a) generative fertilisation
(b) syngamy
(c) vegetative fertilisation
(d) both (a) and (b)
Answer:
(d) both (a) and (b)

Question 40.
The total number of nuclei involved in double fertilisation in angiospersm are
(a) two
(b) three
(c) four
(d) five
Answer:
(d) five

Question 41.
Triple fusion in Capsella bursa pastoris is fusion of male gamete with
(a) egg
(b) synergid
(c) secondary nucleus
(d) antipodal.
Answer:
(c) secondary nucleus

Question 42.
Double fertilisation was first discovered in 1898 by _______ in Fritillaria and Lilium.
(a) Nawaschin
(b) Strasburger
(c) Amici
(d) Focke
Answer:
(a) Nawaschin

Question 43.
If an endosperm cell of an angiosperm contains 24 chromosomes, the number of chromosomes in each cell of the root will be
(a) 8
(b) 4
(c) 16
(d) 24
Answer:
(c) 16

Question 44.
The cells of endosperm have 24 chromosomes. What will be the number of chromosomes in the gametes ?
(a) 8
(b) 16
(c) 23
(d) 32
Answer:
(a) 8

Question 45.
The true embryo develops as a result to fusion of
(a) two polar nuclei of embryo sac
(b) egg cell and male gamete
(c) synergid and male gamete
(d) male gamete and antipodals.
Answer:
(b) egg cell and male gamete

Question 46.
Father of Indian embryology is
(a) P. Maheshwari
(b) Swaminathan
(c) R. Misra
(d) Butler
Answer:
(a) P. Maheshwari

Question 47.
The portion of embryonal axis between plumule (future shoot) and cotyledons is called
(a) hypocotyl
(b) epicotyl
(c) coleorhiza
(d) coleoptile.
Answer:
(b) epicotyl

Question 48.
Coleoptile and coleorhiza are the protective sheaths _______ covering _______ and _______ respectively.
(a) plumule, epicotyl
(b) radicle, plumule
(c) plumule, radicle
(d) radicle, hypocotyl
Answer:
(c) plumule, radicle

Question 49.
_______ is not an endospermic seed.
(a) Pea
(b) Castor
(c) Maize
(d) Wheat
Answer:
(a) Pea

Question 50.
Endosperm is completely consumed by the developing embryo in
(a) pea and groundnut
(b) maize and castor
(c) castor and groundnut
(d) maize and pea.
Answer:
(a) pea and groundnut

Question 51.
Endospermic seeds are found in
(a) castor
(b) barley
(c) coconut
(d) all of these
Answer:
(d) all of these

Question 52.
In albuminous seeds, food is stored in _______ and in non albuminous seeds, it is stored in _______.
(a) endosperm, cotyledons
(b) cotyledons, endosperm
(c) nucellus, cotyledons
(d) endosperm, radicle
Answer:
(a) endosperm, cotyledons

Question 53.
Persistent nucellus is called as _______ and is found in _______.
(a) perisperm, black pepper
(b) perisperm, groundnut ‘
(c) endosperm, black pepper
(d) endosperm groundnut
Answer:
(a) perisperm, black pepper

Question 54.
Indentify the wrong statement regarding post-fertilisation development.
(a) The ovary wall develops into pericarp.
(b) The outer integument of ovule develops into tegmen.
(c) The fusion nucleus (triple nucleus) develops into endosperm.
(d) The ovule develops into seed.
Answer:
(b) The outer integument of ovule develops into tegmen.

Question 55.
Polyembryony commonly occurs in
(a) banana
(b) tomato
(c) potato
(d) citrus.
Answer:
(d) citrus.

Question 56.
An embryo may sometimes develop from any cell of embryo sac other than egg. It is termed as
(a) apospory
(b) apogamy
(c) parthenogenesis
(d) parthenocarpy
Answer:
(b) apogamy

Question 57.
Embryo sac is to ovule as _______ is to an anther.
(a) Stamen
(b) filament
(c) pollen grain
(d) androecium
Answer:
(c) pollen grain

Question 58.
The outermost and innermost wall layers of microsporangium in an anther are respectively
(a) endothecium and tapetum
(b) epidermis and endodermis
(c) epidermis and middle layer
(d) epidermis and tapetum.
Answer:
(d) epidermis and tapetum.

Question 59.
During microsporogenesis, meiosis occurs in
(a) endothecium
(b) microspore mother cells
(c) microspore tetrads
(d) pollen grains
Answer:
(b) microspore mother cells

Question 60.
From among the sets of terms given below, identify those that are associated with the gynoecium.
(a) Stigma, ovule, embryo sac, placenta
(b) Thalamus, pistil, style, ovule
(c) Ovule, ovary, embryo sac, tapetum
(d) Ovule, stamen, ovary, embryo sac
Answer:
(a) Stigma, ovule, embryo sac, placenta

Question 61.
Starting from the innermost part, the correct sequence of parts in an ovule are
(a) egg, nucellus, embryo sac, integument
(b) egg, embryo sac, nucellus, integument
(c) embryo sac, nucellus, integument, egg
(d) egg. integument, embryo sac, nucellus.
Answer:
(b) egg, embryo sac, nucellus, integument

Question 62.
The phenomenon wherein, the ovary develops into a fruit without fertilisation is called
(a) parthenocarpy
(b) apomixis
(c) asexual reproduction
(d) sexual reproduction
Answer:
(a) parthenocarpy

Bihar Board 12th Chemistry Objective Questions and Answers

Bihar Board 12th Chemistry Objective Answers Chapter 4 Chemical Kinetics

Question 1.
When a chemical reaction takes place, during the course of the reaction the rate of reaction
(a) keeps on increasing with time
(b) remains constant with time
(c) keeps on decreasing with time
(d) shows irregular trend with time
Answer:
(c) keeps on decreasing with time

Question 2.
Consider the reaction :
\(2 \mathrm{N}_{2} \mathrm{O}_{4} \rightleftharpoons 4 \mathrm{N} \mathrm{O}_{2}\) \(\frac{\mathrm{d}\left[\mathrm{N}_{2} \mathrm{O}_{4}\right]}{\mathrm{dt}}=\mathrm{k} \text { and } \frac{\mathrm{d}\left[\mathrm{NO}_{2}\right]}{\mathrm{dt}}=k^{\prime}\) then
(a) 2k = k’
(b) k = 2k’
(c) k = k’
(d) k = 1/4 k’
Answer:
(b) k = 2k’

Question 3.
For the reaction 2NH₃ →N₂ + 3H₂, if –\(\frac{\mathrm{d}\left[\mathrm{NH}_{3}\right]}{\mathrm{dt}}=\mathrm{k}_{1}\left[\mathrm{NH}_{3}\right], \frac{\mathrm{d}\left[\mathrm{N}_{2}\right]}{\mathrm{dt}}\) then the relation between k₁, k₂ and k₃ is ………….
(a) k₁= k₂ = &₃
(b) k₁ = 3 k₂ = 2 k₂
(c) 1.5k₁ = 3k₂ = k₃
(d) 2k₁= k₂ = 3k₃
Answer:
(c) 1.5k₁ = 3k₂ = k₃

Question 4.
The rate of disappearance of SO₂ in the reaction, 2SO₂ + O₂ → 2SO₃ is 1.28 x 10^-5 M s^-1. The rate of appearance of SO₃ is …………..
(a) 64 x 10^-5 M s^-1
(b) 0.32 x 10^-5 M s^-1
(c) 2.56 x 10^-5 Ms^-1
(d) 1.28 x 10^-5 M s^-1
Answer:
(d) 1.28 x 10^-5 M s^-1

Question 5.
In a reaction 2X → Y, the concentration of X decreases from 3.0 moles/litre to 2.0 moles/litre in 5 minutes. The rate of reaction is ………………..
(a) 1 mol L^-1 min^-1
(b) 5 mol L^-1 min^-1
(c) 1 mol L^-1 min^-1
(d) 0.5 mol L^-1 min^-1
Answer:
(a) 1 mol L^-1 min^-1

Negative sign signifies the decrease in concentration

Question 6.
The rate constant of a reaction depends upon
(a) temperature of the reaction
(b) extent of the reaction
(c) initial concentration of the reaction
(d) the time of completion of reaction
Answer:
(a) temperature of the reaction

Question 7.
The chemical reaction, 2O₃ → 3O₂ proceeds as
\(\mathbf{O}_{3} \rightleftharpoons \mathbf{O}_{2}+[\mathbf{O}] \text { (fast) }\) [O] + O₃ → 2O₂ (slow) The rate law expression will be ………….
(a) Rate = k[O] [O₃]
(b) Rate = k[O₃]² [O₂]^-1
(c) Rate = it [O₃]²
(d) Rate = k [O₂] [O]
Answer:
(b) Rate = k[O₃]² [O₂]^-1

[O] is unstable intermediate so substitute the value of
[O] in above equation.
Rate of forward reaction = k₁ [O₃]
Rate of backward reaction = [k_-1] [O₂] [O]
At equilibrium,
Rate of forward reaction = Rate of backward reaction

Question 8.
Rate constant in case of first order reaction is
(a) inversely proportional to the concentration units
(b) independent of concentration units
(c) directly proportional to concentration units
(d) inversely proportional to the square of concentration units
Answer:
(b) independent of concentration units

Question 9.
The rate constant for the reaction, 2N₂O_s → 4NO₂ + O₂ is 2 x 10^–5s^-1. If rate of reaction is 1.4 x 10^-5 mol L^-1 s^-1, what will be the concentration of N₂O₅ in mol L^-1?
(a) 8
(b) 0.7
(c) 1.2
(d) 1
Answer:
(b) 0.7
(b) Rate = k[N₂O₅] (first order as unit of rate constant is s^-1)

Question 10.
The order of reaction is decided by…………..
(a) temperature
(b) mechanism of reaction as well as relative concentration of reactants
(c) molecularity
(d) pressure
Answer:
(b) mechanism of reaction as well as relative concentration of reactants

Question 11.
Which of the following is an example of a fraction order reaction ?
(a) NH₄NO₂ → N₂ +2H₂O
(b) NO + O₃ → NO₂+O₂
(c) 2NO + Br₂ → 2NOBr
(d) CH₃CHO → CH₄ + CO
Answer:
(d) CH₃CHO → CH₄ + CO

Question 12.
What will be the rate equation for the reaction 2X + Y→ Z, if the order of the reaction is zero ?
(a) Rate = k[X] [Y]
(b) Rate = k
(c) Rate = A[X]⁰[Y]
(d) Rate = k[X][Y]⁰
Answer:
(b) Rate = k

Question 13.
For a reaction, I^–+ OCl^– → IO^– + Cl^– in an aqueous medium, the rate of reaction is given by \(\frac{\mathrm{d}\left[\mathrm{I} \mathrm{O}^{-}\right]}{\mathrm{dt}}=\mathrm{k} \frac{\left[\mathrm{I}^{-}\right]\left[\mathrm{OCl}^{-}\right]}{\left[\mathrm{OH}^{-}\right]}\) is
(a) – 1
(b) 0
(c) 1
(d) 2
Answer:
(c) 1

Question 14.
The unit of rate constant for the reaction, 2H₂ + 2NO → 2H₂O + N₂ which has rate – k[H₂][NO]², is …………..
(a) molL^–1s^-1
(b) s^-1
(c) mol^–1L²s^-1
(d) mol L^-1
Answer:
(c) mol^–1L²s^-1

(c) Unit of rate constant for the reaction is

Question 15.
The unit of rate and rate constant are same for a…………….
(a) zero order reaction
(b) first order reaction
(c) second order reaction
(d) third order reaction
Answer:
(a) zero order reaction

Question 16.
The number of molecules of the reactants taking part in a single step of the reaction is indicative of
(a) order of a reaction
(b) molecularity of a reaction
(c) fast step of the mechanism of a reaction
(d) half-life of the reaction
Answer:
(b) molecularity of a reaction

Question 17.
The overall rate of a reaction is governed by
(a) the rate of fastest intermediate step
(b) the sum of the rates of all intermediate steps
(c) the average of the rates of all the intermediate steps
(d) the rate of slowest intermediate step.
Answer:
(d) the rate of slowest intermediate step.

Question 18.
The expression to calculate time required for completion of zero order reaction is ………..

Answer:
(a)

Question 19.
A plot, of log (a -x) against time t is a striaght line. This indicates that the reaction is of
(a) zero order
(b) first order
(c) second order
(d) third order
Answer:
(b) first order

Question 20.
Radioactive disintegration is an example of ……………
(a) zero order reaction
(b) first order reaction
(c) second order reaction
(d) third order reaction
Answer:
(b) first order reaction

Question 21.
The rate constant of a first order reaction is 15 x 10^-3 s^-1. How long will 5.0 g of this reactant take to reduce to 3.0 g ?
(a) 07 s
(b) 7.57 s
(c) 10.10 s
(d) 15 s
Answer:
(a) 07 s

Question 22.
A first order reaction is 20% complete in 10 minutes. What is the specific rate constant for the reaction ?
(a) 0970 min^-1
(b) 0.009 min^-1
(c) 0.0223 min^-1
(d) 2.223 min^-1
Answer:
(c) 0.0223 min^-1

Question 23.
A first order reaction takes 40 min for 30% decomposition. What will be t_1/2 ?
(a) 7 min
(b) 52.5 min
(c) 46.2 min
(d) 22.7 min
Answer:
(a) 7 min

Question 24.
A first order reaction has a rate constant 1.15 x 10^-3 s^-1. How long will 5 g of this reaction take to reduce to 3 g ?
(a) 444 s
(b) 400 s
(c) 528 s
(d) 669 s
Answer:
(a) 444 s

Question 25.
Half-life period of a first order reaction is 10 min. What percentage of the reaction will be completed in 100 min ?
(a) 25%
(b) 50%
(c) 99.9%
(d) 75%
Answer:
(c) 99.9%

Question 26.
The rate constant for a first order reaction is 2 x 10^-2 min^-1. The half-life period of reaction is
(a) 69.3 min
(b) 34.65 min
(c) 17.37 min
(d) 3.46 min
Answer:
(b) 34.65 min

Question 27.
The value of rate of a pseudo first order reaction depends upon
(a) the concentration of both the reactants present in the reaction
(b) the concentration of the reactant present in small amount
(c) the concentration of the reactant present in excess
(d) the value of ΔH of the reaction
Answer:
(b) the concentration of the reactant present in small amount

Question 28.
Under what conditions a bi-molecular reaction may be kinetically of first order ?
(a) When both reactants have same concentration
(b) When one of the reacting species is in large excess
(c) When the reaction is at equilibrium
(d) When the activation energy of reaction is less
Answer:
(b) When one of the reacting species is in large excess

Question 29.
The hydrolysis of ethyl acetate, ……………….

(a) zero order
(b) pseudo first order
(c) second order
(d) third order
Answer:
(b) pseudo first order

Question 30.
The temperature dependence of the rate of a chemical reaction can be explained by Arrhenius equation which is…..
(a) k = Ae^E_a/RT
(b) k = Ae-^E_a/RT
(c) K = Ae x \(\frac{\mathrm{E}_{\mathrm{a}}}{\mathrm{RT}}\)
(d) K = Ae x \(\frac{R T}{E_{a}}\)
Answer:
(a) k = Ae^E_a/RT

Question 31.
The energy diagram of a reaction P + Q → R + Sis given. What are A and B in the graph ?

(a) A → activation energy, B → heat of reaction
(b) A → threshold energy, B →heat of reaction
(c) A → heat of reaction, B → activation energy
(d) A →potential energy, B → energy of reaction
Answer:
(a) A → activation energy, B → heat of reaction

Question 32.
For an endothermic reaction, AH represents the enthalpy of the reaction in kj mol^-1. The minimum amount of activation energy will be
(a) less than zero
(b) equal to ΔH
(c) less than ΔH
(d) more than ΔH
Answer:
(d) more than ΔH

Question 33.
The decomposition of a hydrocarbon follows the equation k = (4.5 x 10¹¹ s^-1) e^{-28000 K/T}. What will be the value of activation energy ?
(a) 669 kJ mol^-1
(b) 232.79   kJ mol^-1
(c) 4.5 x 10^-1 kJ mol^-1
(d) 28000 kJ mol^-1
Answer:
(b) 232.79   kJ mol^-1

(b) Arrhenius equation, k = Ae ^Ea^/RT
Given equation is k = (4.5x 10¹¹ s^-1)e^{-28000 K/T}
Comparing both the equations, we get
\(=\frac{E_{a}}{R T}=-\frac{28000 K}{T}\)
E_a = 28000 K x R = 280000 K x 8.314JK^-1mol^-1
= 232.79 kJ mol-¹

Question 34.
The rate constant for a first order reaction at 300°C for which E_a is 35 kcal mol^-1 and frequency constant is 1.45 x 10¹¹ s^-1 is
(a) 10 x 10^-2s^-1
(b) 5.37 x 10¹⁰s^-1
(c) 5 x 10^-4s^-1
(d) 7.94 x 10^-3s^-1
Answer:
(d) 7.94 x 10^-3s^-1

Question 35.
The increase in concentration of the reactants lead to change in
(a) ΔH
(b) collision frequency
(c) activation energy
(d) equilibrium constant
Answer:
(b) collision frequency

Question 36.
The rate constant is given by the equation k = P.Ze^-Ea/RT  Which factor should register a decrease for the reaction to proceed more rapidly ?
(a) T
(b) Z
(c) E
(d) P
Answer:
(c) E

Question  37.
Threshold energy is equal to ……………
(a) activation energy
(b) activation energy – energy of molecules
(c) activation energy + energy of molecules
(d) None of these
Answer:
(c) activation energy + energy of molecules

Question 38.
The role of a catalyst is to change………………..
(a) Gibbs energy of reaction
(b) enthalpy of reaction
(c) activation energy of reaction
(d) equilibrium constant
Answer:
(c) activation energy of reaction

Question 39
In the presence of a catalyst, the heat evolved or absorbed during the reaction…………..
(a) increases
(b) decreases
(c) remains unchanged
(d) may increase or decrease
Answer:
(c) remains unchanged

Question 40.
A first order reaction is 50% completed in 1.26 x 10¹⁴ How much time would it take for 100% completion ?
(a) 1.26 x 10¹⁵ s
(b) 2.52 x 10¹⁴ s
(c) 2.52 x 10²⁸ s
(d) Infinite
Answer:
(d) Infinite

Bihar Board 12th Physics Objective Questions and Answers

Bihar Board 12th Physics Objective Answers Chapter 14 Semiconductor Electronics: Materials, Devices and Simple Circuits

Question 1.
At absolute zero, Si acts as a
(a) metal
(b) Semiconductor
(c) insulator
(d) None of these
Answer:
(c) insulator

Question 2.
In good conductors of electricity the type of bonding that exist is
(a) van der Walls
(b) covalent
(c) ionic
(d) metallic
Answer:
(d) metallic

Question 3.
The manifestation of band structure in solids is due to
(a) Heisenberg uncertainty principle
(b) Pauli’s exclusion principle
(c) Bohr’s correspondence principle
(d) Boltzmann law
Answer:
(b) Pauli’s exclusion principle

Question 4.
The probability of electrons to be found in the conduction band of an intrinsic semicondutor of finite temperature
(a) increases exponentially with increasing band gap
(b) decreases exponentially with increasing band gap
(c) decreases with increasing temperature
(d) is independent of the temperature and band gap
Answer:
(b) decreases exponentially with increasing band gap

Question 5.
In n-type semiconductor when all donor states are filled, then the net charge density in the donor states becomes
(a) 1
(b) > 1
(c) < 1, but not zero
(d) zero
Answer:
(b) > 1

Question 6.
A semiconductor has equal electron and hole concentration of 6 x 108 per m3. On doping with certain impurity, electron concentration increases to 9 x 1012 per m3. The new hole concentration is
(a) 2 x 10⁴ per m³
(b) 2 x 10² per m³
(c) 4 x 10⁴ per m³
(d) 4x 10² perm³
Answer:
(c) 4 x 10⁴ per m³

Question 7.
The dominant mechanism for motion of charge carriers in forward and reverse biased silicon p-n junction are
(a) drift in forward bias, diffusion in reverse bias
(b) diffusion in forward bias, drifit in reverse bias
(c) diffusion in both forward and reverse bias
(d) drift in both forward and reverse bias
Answer:
(b) diffusion in forward bias, drifit in reverse bias

Question 8.
Region without free electrons and holes in a p-n junction is
(a) n-region
(b) p-region
(c) depletion region
(d) none of these
Answer:
(c) depletion region

Question 9.
Potential barrier developed in a junction diode opposes the flow of
(a) minority carrier in both regions only
(b) majority carriers only
(c) electrons in p region
(d) holes in p region
Answer:
(b) majority carriers only

Question 10.
A potential barrier of 0.3 V exists across a p-n junction. If the depletion region is 1 pm wide, what is the intensity of electric field in this region ?
(a) 2 x 10⁵ V m^-1
(b) 3 x 10⁵ V m^-1
(c) 4 x 10⁵ V m^-1
(d) 5 x 10⁵ V m^-1
Answer:
(b) 3 x 10⁵ V m^-1

Question 11.
A forward-biased diode is

Answer:
(a)

Question 12.
When the voltage drop across a p-n junction diode is increased from 0.65 V to 0.70 V, the change in the diode current is 5 mA. The dynamic resistance of the diode is
(a) 5 Ω
(b) 10 Ω
(c) 20 Ω
(d) 25 Ω
Answer:
(b) 10 Ω

Question 13.
In the circuit shown if current for the diode is 20 pA, the potential difference across the diode is

(a) 2 V
(b) 4.5 V
(c) 4 V
(d) 2.5 V
Answer:
(c) 4 V

Question 14.
The equivalent resistance of the circuit shown in figure between the points A and B if V_A < V_B is

(a) 10 Ω
(b) 20 Ω
(c) 5 Ω
(d) 40 Ω
Answer:
(b) 20 Ω

Question 15.
In the question number 34, the equivalent resistance between the points A and B, if V_A > V_B is
(a) 10 Ω
(b) 20 Ω
(c) 30 Ω
(d) 15 Ω
Answer:
(a) 10 Ω

Question 16.
In a half wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be
(a) 25 Hz
(b) 50 Hz
(c) 70.7 Hz
(d) 100 Hz
Answer:
(b) 50 Hz

Question 17.
What happens during regulation action of a Zener diode?
(a) The current through the series resistance (R_S) changes
(b) The resistance offered by the Zener changes
(c) The Zener resistance is constant
(d) Both (a) and (b)
Answer:
(d) Both (a) and (b)

Question 18.
From the Zener diode circuit shown in figure, the current through the Zener diode is

(a) 34 mA
(b) 31.5 mA
(c) 36.5 mA
(d) 2.5 mA
Answer:
(b) 31.5 mA

Question 19.
A p-n photodiode is fabricated from a semiconductor with a band gap of 2.5 eV. The signal wavelength is
(a) 6000 A
(b) 6000 nm
(c) 4000 nm
(d) 5000 A
Answer:
(d) 5000 A

Question 20.
The transfer characteristics of a base biased transistor has the operation regions, namely, cutoff, active region and saturation region. For using the transistor as an amplifier it has to operate in the
(a) active region
(b) cutoff region
(c) saturation region
(d) cutoff and saturation
Answer:
(a) active region

Question 21.
The emitter of transistor is doped the heaviest because it
(a) acts as a supplier of charge carriers
(b) dissipates maximum power
(c) has a larger resistance
(d) has a small resistance
Answer:
(a) acts as a supplier of charge carriers

Question 22.
The heavily and lightly doped regions of a bipolar junction transistor are respectively
(a) base and emitter
(b) base and collector
(c) emitter and base
(d) collector and emitter
Answer:
(c) emitter and base

Question 23.
An oscillator is nothing but an amplifier with
(a) larger gain
(b) positive feedback
(c) no feedback
(d) negative feedback
Answer:
(b) positive feedback

Question 24.
The current amplification factor a of a common base transistor and the current amplification factor 3 of a common emitter transistor are not related by

Answer:
(d)

Question 25.
If a and 3 are the current gain in the CB and CE configurations respectively of the transistor circuit, then \(\frac{\beta-\alpha}{\alpha \beta}=\)
(a) zero
(b) 1
(c) 2
(d) 0.5
Answer:
(b) 1

Question 26.
A transistor connected in common emitter mode, the voltage drop across the collector is 2 V and 3 is 50, the base current if Rc is 2 kΩ is
(a) 40 μA
(b) 20 μA
(c) 30 μA
(d) 15 μA
Answer:
(b) 20 μA

Question 27.
The current gain for a common emitter amplifier is 69. If the emitter current is 7 mA, the base current is
(a) 0.1 m A
(b) 1 mA
(c) 0.2 m A
(d) 2 mA
Answer:
(a) 0.1 m A

Question 28.
The ac current gain of a transistor is 120. What is the change in the collector current in the transistor whose base current changes by 100 μA ?
(a) 6 mA
(b) 12 mA
(c) 3 mA
(d) 24 mA
Answer:
(b) 12 mA

Question 29.
In an n-p-n circuit transistor, the collector current is 10 mA. If 80% electron emitted reach the collector, then
(a) the emitter current will be 7.5 mA
(b) the emitter current will be 12.5 mA
(c) the base current will be 3.5 mA
(d) the base current will be 1.5 mA
Answer:
(b) the emitter current will be 12.5 mA

Question 30.
A transistor has a current gain of 30. If the collector resistance is 6 kΩ, input resistance is 1 kΩ, it voltage gain is
(a) 90
(b) 180
(c) 45
(d) 360
Answer:
(b) 180

Question 31.
In a transistor connected in common emitter mode, R_c =4 kΩ, R₁ = 1 kΩ, I_c = 1 mA and IB = 20μA. The voltage gain is
(a) 100
(b) 200
(c) 300
(d) 400
Answer:
(b) 200

Question 32.
In an n-p-n transistor 10¹⁰ electron enter the emitter in 10^-6 s. If 2% of the electrons are lost in the base, the current amplification factor is
(a) 0.02
(b) 7
(c) 33
(d) 4.9
Answer:
(a) 0.02

Question 33.
If a change of 100 pA in the base current of an n-p-n transistor causes a change of 10 mA in its collector current, its ac current gain is
(a) 50
(b) 100
(c) 200
(d) 150
Answer:
(b) 100

Question 34.
What is the voltage gain in a common emitter amplifier, where input resistance is 3Ω and load resistance 24 Ω and β = 61 ?
(a) 8.4
(b) 488
(c) 240
(d) 0
Answer:
(b) 488

Question 35.
An amplifier has a voltage gain of 100. The voltage gain in dB is
(a) 20 dB
(b) 40 dB
(c) 30dB
(d) 50dB
Answer:
(b) 40 dB

Question 36.
Boolean algebra is essentially based on
(a) number
(b) truth
(c) logic
(d) symbol
Answer:
(c) logic

Question 37.
The symbolic representation of four logic gates are given below. The logic symbols for OR, NOT and NAND gates are respectively.


(a) (i v), (i), (ii i)
(b) (i v), (ii), (i)
(c) (i), (iii), (iv)
(d) (iii), (iv), (ii).
Answer:
(b) (i v), (ii), (i)

Question 38.
Study the circuit shown in the figure. Name the gate that the given circuit resembles.

(a) NAND
(b) AND
(c) OR
(d) NOR
Answer:
(b) AND

Question 39.
In Boolean algebra if A = 1 and B = 0, then the value of A + \(\bar{B}\) is
(a) A
(b) A.B
(c) A + B
(d) both (a) and (c)
Answer:
(d) both (a) and (c)

Question 40.
What will be input of A and B for the Boolean expression \((\overline{A+B}) \cdot(\overline{A \cdot B})=1 ?\)?
(a) (0, 0)
(b) (0, 1)
(c) (1, 0)
(d) (1, 1)
Answer:
(a) (0, 0)

Question 41.
The circuit given in figure, is equivalent to

(a) AND gate
(b) OR gate
(c) NOT gate
(d) NAND gate
Answer:
(a) AND gate

Question 42.
The given truth table is for which logic gate ?

(a) NAND
(b) XOR
(c) NOR
(d) OR
Answer:
(a) NAND

Question 43.
The decimal equivalent of the binary number (11010.101) 2is
(a) 9.625
(b) 25.265
(c) 26.625
(d) 26.265
Answer:
(d) 26.265

Question 44.
Hole is
(a) an anti-particle of electron.
(b) a vacancy created when an electron leaves a covalent bond.
(c) absence of free electrons.
(d) an artificially created particle.
Answer:
(b) a vacancy created when an electron leaves a covalent bond.

Question 45.
In the circuit shown in figure, if the diode forward voltage drop is 0.3 V, the voltage difference between A and B is
(a) 1.3 V
(b) 2.3 V
(c) 0
(d) 0.5V
Answer:
(b) 2.3 V

Hints & Explanations

Question 6.

Question 12.
(b) Dynamic resistance is \(r_{d}=\frac{\Delta V}{\Delta I}\)
Answer:
Here, ΔV = 0.7 – 0.65 V = 0.05 V,
ΔI = 5 mA = 5 x 10^-3 A
∴ \(r_{d}=\frac{0.05}{5 \times 10^{-3}}=10 \Omega\)

Question 13.
(c) Since the diode is reversed biased, only drift current exists in circuit which is 20 pA.
Answer:
Potential drop across 15 Ω resistor
= 15 Ω x 20 μA
= 300 μV = 0.0003 V
Potential difference across the diode
= 4 – 0.0003
= 3.99 = 4V

Question 14.
(b) When V_A < V_B, the diode gets reverse biased and offers infinite resistance. No current flows through the upper branch
∴ R = 20 Ω

Question 18.
(b) Here, R_L = 5 x 10³ Ω, V, = 220 V,
Zener voltage, V_Z = 50 V
Answer:

Question 19.
(d) The detection occurs only when the energy of incident photon greater than or equal to the energy band gap
Answer:

Question 25.
(b) Since P = \(\beta=\frac{\alpha}{1-\alpha}\)
Answer:

Question 26.

Question 27.
(a) Current gain, \(\beta=\frac{I_{C}}{I_{B}}\)
Answer:
For common emitter configuration, I_E = I_c

Question 28.

Question 29.

Question 30.
(b) Voltage gain = current gain x resistance gain
= current gain \(\times \frac{R_{C}}{R_{I}}=30 \times \frac{6}{1}=180\)

Question 31.
(b) Voltage gain,
Answer:

Question 32.
(a) As, \(I_{E}=\frac{n_{E} \times e}{t}\)

Question 33.
(b) Here, \(\Delta I_{B}=100 \mu \mathrm{A}=100 \times 10^{-6} \mathrm{A}\) 

Question 34.
(b) Voltage gain, \(A_{V}=\beta \frac{R_{o}}{R_{i}}=\frac{61 \times 24}{3}=488\)

Bihar Board 12th Biology Objective Questions and Answers

Bihar Board 12th Biology Objective Answers Chapter 5 Principles of Inheritance and Variation

Question 1.
The colour based contrasting traits in seven contrasting pairs, studied by Mendel in pea plant were
(a) 1
(b) 2
(c) 3
(d) 4
Answer:
(c) 3

Question 2.
_________ pairs of contrasting traits were studied by Mendel in pea plant.
(a) 6
(b) 7
(c) 8
(d) 10
Answer:
(b) 7

Question 3.
Which of the following characters was not chosen by Mendel ?
(a) Pod shape
(b) Pod colour
(c) Location of flower
(d) Location of pod
Answer:
(d) Location of pod

Question 4.
Genes which code for a pair of contrasting traits are known as
(a) dominant genes
(b) alleles
(c) linked genes
(d) none of these
Answer:
(b) alleles

Question 5.
A recessive allele is expressed in
(a) heterozygous condition only
(b) homozygous condition only
(c) F3 generation
(d) both homozygous and heterozygous conditions.
Answer:
(b) homozygous condition only

Question 6.
The characters which appear in the first filial generation are called
(a) recessive characters
(b) dominant characters
(c) holandric characters
(d) lethal characters
Answer:
(b) dominant characters

Question 7.
What will be the distribution of phenotypic features in the first filial generation after a cross between a homozygous female and a heterozygous male for a single locus ?
(a) 3 : 1
(b) 1 : 2 : 1
(c) 1 : 1
(d) None of these
Answer:
(c) 1 : 1

Question 8.
In a monohybrid cross between two heterozygous individuals, percentage of pure homozygous individuals obtained in F₁ generation will be
(a) 25 %
(b) 50 %
(c) 75 %
(d) 100 %
Answer:
(b) 50 %

Question 9.
What is the probability of production of dwarf offsprings in a cross betweeen two heterozygous tall pea plants ?
(a) Zero
(b) 50 %
(c) 25 %
(d) 100 %
Answer:
(c) 25 %

Question 10.
Which of the following crosses will give tall and dwarf pea plants in same proportions ?
(a) TT × tt
(b) Tt × tt
(c) TT × Tt
(d) tt × tt
Answer:
(b) Tt × tt

Question 11.
To determine the genotype of a tall plant of F₂ generation, Mendel crossed this plant with a dwarf plant. This cross represents a
(a) test cross
(b) back cross
(c) reciprocal cross
(d) dihybrid cross.
Answer:
(a) test cross

Question 12.
Which of the following is a test cross ?
(a) TT × TT
(b) Tt × Tt
(c) tt × tt
(d) Tt × tt
Answer:
(d) Tt × tt

Question 13.
Mendal formulated the law of purity of gametes on the basis of
(a) monohybrid cross
(b) dihybrid cross
(c) test cross
(d) back cross.
Answer:
(a) monohybrid cross

Question 14.
The inheritance of flower colour in Antirrhinum (dog flower) is an example of
(a) incomplete dominance
(b) co-dominance
(c) multiple alleles
(d) linkage.
Answer:
(a) incomplete dominance

Question 15.
In Antirrhinum (dog flower), phenotypic ratio in F₂ generation for the inheritance of flower colour would be
(a) 3 : 1
(b) 1 : 2 : 1
(c) 1 : 1
(d) 2 : 1
Answer:
(b) 1 : 2 : 1

Question 16.
Phenotypic and genotypic ratio is similar in case of
(a) complete dominance
(b) incomplete dominance
(c) over dominance
(d) epistasis.
Answer:
(b) incomplete dominancec

Question 17.
What can be the blood group of offspring when both parents have AB blood group ?
(a) AB only
(b) A, B and AB
(c) A, B, AB and O
(d) A and B only
Answer:
(b) A, B and AB

Question 18.
Inheritance of roan coat in cattle is an example of
(a) incomplete dominance
(b) codominance
(c) multiple allelism
(d) none of these
Answer:
(b) codominance

Question 19.
ABO blood grouping in human beings cites the example of
(a) incomplete dominance
(b) co-dominance
(c) multiple allelism
(d) both
(b) and (c)
Answer:
(b) and (c)

Question 20.
In mice, Y is the dominant allele for yellow fur an y is the recessive allele for grey fur. Since Y is lethal when homozygous, the result of cross Yy × Yy will be
(a) 3 yellow : 1 grey
(b) 2 yellow : 1 grey
(c) 1 yellow : 1 grey
(d) 1 yellow : 2 grey
Answer:
(b) 2 yellow : 1 grey

Question 21.
In Mendelian dihybrid cross, when heterozygous Round Yellow are self crossed, Round Green offsprings are represented by the genotype
(a) RrYy, RrYY, RRYy
(b) Rryy, RRyy, rryy
(c) rrYy, rrYY
(d) Rryy, RRyy
Answer:
(d) Rryy, RRyy

Question 22.
The percentage of ab gamete produced by AaBb parent will be
(a) 25 %
(b) 50 %
(c) 75 %
(d) 12.5 %
Answer:
(a) 25 %

Question 23.
How many types of gametes can be produced by a diploid organism who is heterozygous for 4 loci ?
(a) 4
(b) 8
(c) 16
(d) 32
Answer:
(c) 16

Question 24.
Which of the following is correct for the condition when plant YyRr is back crossed with the double recessive parent ?
(a) 9 : 3 : 3 : 1 ratio of phenotypes only
(b) 9 : 3 : 3 : 1 ratio of genotypes only
(c) 1 : 1 : 1 : 1 ratio of phenotypes only
(d) 1 : 1 : 1 : 1 ratio of phenotypes and genotypes
Answer:
(d) 1 : 1 : 1 : 1 ratio of phenotypes and genotypes

Question 25.
Law of independent assortment can be explained with the help of
(a) dihybrid
(b) test cross
(c) back cross
(d) monohybrid cross
Answer:
(a) dihybrid

Question 26.
Mendel’s work was rediscovered by three scientists in the year
(a) 1865
(b) 1900
(c) 1910
(d) 1920
Answer:
(b) 1900

Question 27.
Which three scientists independently rediscovered Mendel’s work ?
(a) Avery, McLeod, McCarty
(b) Sutton, Morgan and Bridges
(c) Bateson, Punnet and Bridges
(d) de Vries, Correns and Tschemark
Answer:
(d) de Vries, Correns and Tschemark

Question 28.
Chromosomal theory of inheritance was given by
(a) Morgan et al
(b) Sutton and Boveri
(c) Hugo deVries
(d) Gregor J. Mendel
Answer:
(b) Sutton and Boveri

Question 29
Experimental verification of ‘chromosomal theory of inheritance’ was done by
(a) Sutton and Boveri
(b) Morgan et al
(c) Henking
(d) Karl Correns.
Answer:
(b) Morgan et al

Question 30.
Genes located very close to one another on same chromosome tend to be transmitted together and are called as
(a) allelomorphs
(b) identical genes
(c) linked genes
(d) recessive genes
Answer:
(c) linked genes

Question 31.
What is true about the crossing over between linked genes ?
(a) No crossing over at all
(b) High percentage of crossing over
(c) Hardly any crossing over
(d) None of these
Answer:
(c) Hardly any crossing over

Question 32.
Chromosome maps/genetic maps were first prepared by
(a) Sutton and Boveri (1902)
(b) Bateson and Punnett (1906)
(c) Morgan (1910)
(d) Sturtevant (1911)
Answer:
(d) Sturtevant (1911)

Question 33.
The distance between the genes is measured by
(a) angstrom
(b) map unit
(c) Dobson unit
(d) millimetre
Answer:
(c) Dobson unit

Question 34.
Which of the following is suitable for experiment on linkage ?
(a) aaBB x aaBB
(b) AABB x aabb
(c) AaBb x AaBb
(d) AAbb x AaBB
Answer:
(b) AABB x aabb

Question 35.
Mendel’s law of independent assortment does not hold true for the genes that are located closely on
(a) same chromosome
(b) non-homologous chromosomes
(c) X-chromosome
(d) autosomes
Answer:
(a) same chromosome

Question 36.
If linkage was known at the time of Mendel then which of the following laws, he would not have been able to explain ?
(a) Law of dominance
(b) Law of independent assortment
(c) Law of segregation
(d) Law of purity of gametes
Answer:
(b) Law of independent assortment

Question 37.
Which of the following are reasons for Mendel’s success ?
(i) Usage of pure lines or pure breeding varieties
(ii) Consideration of one character at a time
(iii) Maintenance of statistical records of experiments
(iv) Knowledge of linkage and incomplete dominance
(a) (i) and (ii) only
(b) (i), (ii) and (iii)
(c) (i) and (iv) only
(d) (ii), (iii) and (iv)
Answer:
(b) (i), (ii) and (iii)

Question 38.
XO type of sex determination and XY type of sex determination are the examples of
(a) male heterogamety
(b) female heterogamety
(c) male homogamety
(d) both (b) and (c)
Answer:
(a) male heterogamety

Question 39.
Grasshopper is an example of XO type of sex determination in which the males have
(a) one X chromosome
(b) one Y chromosome
(c) two X chromosomes
(d) no X chromosome
Answer:
(a) one X chromosome

Question 40.
In XO type of sex determination
(a) females produce two different types of gametes
(b) males produce two different types of gametes
(c) females produce gametes with Y chromosome
(d) males produce gametes with Y chromosome.
Answer:
(b) males produce two different types of gametes

Question 41.
Which of the following is incorrect regarding ZW – ZZ type of sex determination ?
(a) It occurs in birds and some reptiles.
(b) Females are homogametic and males are heterogametic.
(c) 1:1 sex ratio is produced in the offsprings.
(d) All of these
Answer:
(b) Females are homogametic and males are heterogametic.

Question 42.
A couple has six daughters. What is the possibility of their having a girl next time ?
(a) 10 %
(b) 50 %
(c) 90 %
(d) 100 %
Answer:
(b) 50 %

Question 43.
Number of autosomes present in liver cells of a human female is
(a) 22 autosomes
(b) 22 pairs
(c) 23 autosomes
(d) 23 pairs
Answer:
(b) 22 pairs

Question 44.
Haplodiploidy is found in
(a) grasshoppers and cockroaches
(b) birds and reptiles
(c) butterflies and moths
(d) honeybees, ants and waspe.
Answer:
(d) honeybees, ants and waspe.

Question 45.
Rate of mutation is affected by
(a) temperature
(b) X-rays
(c) gamma rays
(d) all of these.
Answer:
(d) all of these.

Question 46.
Two or more independent genes present on different chromosomes which determine nearly same phenotype are called
(a) supplementary genes
(b) complementary genes
(c) duplicate genes
(d) none of these.
Answer:
(c) duplicate genes

Question 47.
Select the incorrect statement regarding pedigree analysis.
(a) Solid symbols show unaffected individuals.
(b) Proband is the person from which case history starts.
(c) It is useful for genetic counsellors.
(d) It is an analysis of traits in several generations of a family.
Answer:
(a) Solid symbols show unaffected individuals.

Question 48.
Which one is the incorrect match ?

Answer:

Question 49.
________ is an example of X-linked recessive trait.
(a) Phenylketonuria
(b) Haemophilia
(c) Cystic fibrosis
(d) Sickle-cell anaemia
Answer:
(b) Haemophilia

Question 50.
Result of a cross between a normal homozygous female and a haemophiliac male would be
(a) normal males and normal females
(b) haemophilic males and normal females
(c) normal males and carrier females
(d) haemophilic males and carrier females.
Answer:
(c) normal males and carrier females

Question 51.
Father of a child is colourblind and mother is carrier for colourblindness, the probability of the child being colour blind is
(a) 25 %
(b) 50 %
(c) 100 %
(d) 75 %
Answer:
(b) 50 %

Question 52.
A marriage between a colourblind man and a normal woman produces
(a) all carrier daughters and normal sons
(b) 50% carrier daughters, 50% normal daughters
(c) 50% colourblind sons, 50% normal sons
(d) all carrier offsprings.
Answer:
(a) all carrier daughters and normal sons

Question 53.
Which of the following is not an example of recessive autosomal disease ?
(a) Haemophilia
(b) Cystic fibrosis
(c) Phenylketonuria
(d) Sickle-cell anaemia
Answer:
(a) Haemophilia

Question 54.
If both parents are carriers for thalassaemia, which is an autosomal recessive disorder, what are the chances of pregnancy resulting in an affected child ?
(a) 25 %
(b) 100 %
(c) No chance
(d) 50 %
Answer:
(a) 25 %

Question 55.
Select the disease which is caused by recessive autosomal genes when present in homozygous conditions.
(a) Alkaptonuria
(b) Albinism
(c) Cystic fibrosis
(d) All of these
Answer:
(d) All of these

Question 56.
Which of the following trait is controlled by dominant autosomal genes ?
(a) Polydactyly
(b) Huntington’s chorea
(c) PTC (phenylthiocarbamide) tasting
(d) All of these
Answer:
(d) All of these

Question 57.
Failure of segregation of chromatids during cell division results in the gain or loss of chromosomes, this is called as
(a) euploidy
(b) monoploidy
(c) aneuploidy
(d) polyploidy
Answer:
(c) aneuploidy

Question 58.
Trisomy is represented by
(a) (2n – 1)
(b) (2n – 2)
(c) (2n + 2)
(d) (2n + 1)
Answer:
(d) (2n + 1)

Question 59.
Mongolism is a genetic disorder which is caused by the presence of an extra chromosome number
(a) 20
(b) 21
(c) 17
(d) 23
Answer:
(b) 21

Question 60.
Klinefelter’s syndrome is characterised by a karyotype of
(a) XYY
(b) XO
(c) XXX
(d) XXY
Answer:
(d) XXY

Question 61.
This abnormality occurs due to monosomy (2n – 1); the individual has 2n = 45 chromosomes with 44 + XO genotype.
(a) Edward’s syndrome
(b) Down’s syndrome
(c) Turner’s syndrome
(d) Klinefelter’s syndrome
Answer:
(c) Turner’s syndrome

Question 62.
Females with Turner’s syndrome have
(a) small uterus
(b) rudimentary ovaries
(c) underdeveloped breasts
(d) all of these.
Answer:
(d) all of these.

Question 63.
All genes located on the same chromosome
(a) form different groups depending upon their relative distance
(b) form one linkage group
(c) will not from any linkage groups
(d) form interactive groups that affect the phenotype.
Answer:
(b) form one linkage group

Question 64.
Conditions of a karyotype 2n±l and 2n + 2 are called
(a) aneuploidy
(b) polyploidy
(c) allopolyploidy
(d) monosomy.
Answer:
(a) aneuploidy

Question 65.
Distance between the genes and percentage of recontbfnatidnshows
(a) a direct relationship
(b) an inverse relationship
(c) a parallel relationship
(d) no relationship.
Answer:
(a) a direct relationship

Question 66.
If a genetic disease is transferred from a phenotypically normal but carrier female to only some of the male progeny, the disease is
(a) autosomal dominant
(b) autosomal recessive
(c) sex-linked dominant
(d) sex-linked recessive.
Answer:
(d) sex-linked recessive.

Question 67.
In sickle cell anaemia glutamic acid is replaced by valine. Which one of the following triplets codes for valine?
(a) GGG
(b) A AG
(c) G A A
(d) GUG
Answer:
(d) GUG

Question 68.
Person having genotype IA IB would show the blood group as AB. This is because of
(a) pleiotropy
(b) co-dominance
(c) segregation
(d) incomplete dominance.
Answer:
(b) co-dominance

Question 69.
ZZ/ZW type of sex determination is seen in
(a) platypus
(b) snails
(c) cockroach
(d) peacock
Answer:
(d) peacock

Question 70.
A cross between two tall plants resulted in offspring having few dwarf plants. What would be the genotypes of both the parents?
(a) TT and Tt
(b) Tt and Tt
(c) TT and TT
(d) Tt and It
Answer:
(b) TtandTt

Question 71.
In a dihybrid cross, if you get 9 : 3 : 3 : 1 ratio it denotes that
(a) the alleles of two genes are interacting with each other
(b) it is a multigenic inheritance
(c) it is a case of multiple allelism
(d) the alleles of two genes are segregating independently.
Answer:
(d) the alleles of two genes are segregating independently.

Question 72.
Which of the following will not result in variations among siblings?
(a) Independent assortment of genes
(b) Crossing over
(c) Linkage
(d) Mutation
Answer:
(c) Linkage

Question 73.
Mendel’s Law of independent assortment holds good for genes situated on the
(a) non-homologous chromosomes
(b) homologous chromosomes
(c) extranuclear genetic element
(d) same chromosome.
Answer:
(b) homologous chromosomes

Question 74.
Occasionally, a single gene may express more than one effect. The phenomenon is called
(a) multiple allelism
(b) mosaicism
(c) pleiotropy
(d) polygeny.
Answer:
(c) pleiotropy

Question 75.
In the F2 generation of a Mendelian dihybrid cross the number of phenotypes and genotypes are
(a) phenotypes – 4; genotypes – 16
(b) phenotypes – 9; genotypes – 4
(c) phenotypes – 4; genotypes – 8
(d) phenotypes – 4; genotypes – 9.
Answer:
(d) phenotypes – 4; genotypes – 9.

Bihar Board 12th Business Studies Model Papers

Bihar Board 12th Business Studies Model Question Paper 1 in English Medium

Time : 3 Hour 15 Min
Full Marks : 100

Instructions

1. Candidates are required to give their answers in their own words as far as practicable.
2. Figures in the right hand margin indicate full marks.
3. 15 minutes of extra time has been allotted for the candidate to read the questions carefull.
4. This question paper has two sections : Section -A and Section-B.
5. In Section-A, there are 50 objective type questions which are compulsory, each carrying 1 mark. Darken the circle with black/blue ball pen against the correct option on OMR Sheet provided to you. Do not use Whitener/ Liquid/Blade/Nail on OMR Sheet, otherwise the result will be treated as invalid.
6. In Section-B, there are 25 Short answer type questions, out of which any 15 questions are to be answered. Each question carries 2 marks. Apart from this, there are 08 Long answer type questions, out-of which any 04 of them are to be answered. Each question carries 5 marks.
7. Use of any electronic device is prohibited.

Objective Type Questions

Question No. 1 to 50 have four options provided, out of which only one is correct. You have to mark, your selected option, on the OMR-Sheet. Each question carries 1 (one) mark. [50 x 1 = 50]

Question 1.
The essence of management is :-
(a) Co-ordination
(b) Organisation
(c) Staffing
(d) All of these
Answer:
(a) Co-ordination

Question 2.
New Economic Ploicy is :-
(a) Liberalisation
(b) Privatisation
(c) Globalisation
(d) All of these
Answer:
(d) All of these

Question 3.
The organization steps are :-
(a) 2
(b) 4
(c) 6
(d) 8
Answer:
(b) 4

Question 4.
Training is a process
(a) Current
(b) Regular
(c) Continuous
(d) All of these
Answer:
(d) All of these

Question 5.
Controlling is necessary in :-
(a) Small enterprise
(b) Medium Enterprise
(c) Large Enterprise
(d) All of the above
Answer:
(d) All of the above

Question 6.
Characteristics of a sound financial planning are: –
(a) Simplicity
(b) Liquidity
(c) Economy
(d) All of these
Answer:
(d) All of these

Question 7.
First Function of financial management is :-
(a) Procurement of fund
(b) Financial forecasting
(c) Financial Control
(d) None of these
Answer:
(a) Procurement of fund

Question 8.
Co-ordination is :-
(a) Voluntary
(b) Necessary
(c) Unecessary
(d) Wastage of time
Answer:
(b) Necessary

Question 9.
By Scientific Management profits are :-
(a) Increased
(b) Decreased
(c) Not affected
(d) Revival
Answer:
(a) Increased

Question 10.
Economic Environment ofbusiness is influenced by :
(a) Economic policy
(b) Economic system
(c) Economic development
(d) All of these
Answer:
(d) All of these

Question 11.
Staffing is the responsibility of.
(a) Lower management
(b) Middle management
(c) Top management
(d) All of these
Answer:
(d) All of these

Question 12.
According to George R. Terry, The type of planning are :-
(a) 08
(b) 06
(c) 04
(d) 02
Answer:
(d) 02

Question 13.
An organization is not helpful lor :-
(a) Co-ordination
(b) Contributes to morale
(c) Increase in corruption
(d) Incentive to growth
Answer:
(c) Increase in corruption

Question 14.
Employees Training is :-
(a) Necessary
(b) Unnecessary
(c) Compulsory
(d) Wastage of Money
Answer:
(c) Compulsory

Question 15.
Direction is related to employees :-
(a) Top level
(b) Middle level
(c) Lower level
(d) All level of above
Answer:
(d) All level of above

Question 16.
Organising process involves :-
(a) Grouping of indentical work
(b) Division of a work
(c) Assigning work to appropriate persons
(d) All of these
Answer:
(d) All of these

Question 17.
Fixed-capital is required for :-
(a) Payment of routine expenses
(b) Purchase of land
(c) Depositing in bank
(d) Payment to creditors
Answer:
(b) Purchase of land

Question 18.
SEBI is controller of :-
(a) Production
(b) Insider trading
(c) Capital marketing
(d) Government
Answer:
(c) Capital marketing

Question 19.
Entrepreneurship is an effort to create :-
(a) Risk
(b) Profit
(c) Jobs
(d) Business
Answer:
(c) Jobs

Question 20.
Working non-government organization in India is :-
(a) VOICE
(b) Common Cause
(c) A and B both
(d) None of these
Answer:
(c) A and B both

Question 21.
The Advantage of marketing is to :-
(a) Consumers
(b) Businessmen
(c) Manufacturers
(d) All of these
Answer:
(d) All of these

Question 22.
Onwner’s Fund does not indued :-
(a) Share Capital
(b) Bank Loan
(c) Reserve Fund
(d) Share Premium
Answer:
(b) Bank Loan

Question 23.
Labelling is :-
(a) Compulsory
(b) Necessary
(c) Voluntary
(d) Wastage of Money
Answer:
(a) Compulsory

Question 24.
Consumer rights under Consumer Protection Act. are :-
(a) 08
(b) 07
(c) 06
(d) 10
Answer:
(a) 08

Question 25.
Social and economic development of a nation is the result of :-
(a) Entrepreneur
(b) Planning
(c) Operation
(d) Government
Answer:
(a) Entrepreneur

Question 26.
Advertising is done for :-
(a) Development of business
(b) Financial management
(c) Sales promotion
(d) Public relations
Answer:
(c) Sales promotion

Question 27.
Maximum period of treasury bill is :-
(a) One year
(b) Two years
(c) Five years
(d) Ten years
Answer:
(a) One year

Question 28.
Supervision is :-
(a) Necessary
(b) Unnecessary
(c) Wastage of time
(d) None of these
Answer:
(a) Necessary

Question 29.
Controlling is the function of
(a) Supervisor
(b) Sales man
(c) Mariager
(d) Employee
Answer:
(a) Supervisor

Question 30.
Steps Involved in selection process :-
(a) 07
(b) 09
(c) 06
(d) 10
Answer:
(a) 07

Question 31.
Depends on the sweet will of employees :-
(a) Divisional organisation
(b) Formal organisation
(c) Functional organisation
(d) Informal organization
Answer:
(d) Informal organization

Question 32.
Planning is not :-
(a) Mental exercise
(b) Forward looking
(c) Wastage of time
(d) Choosing process
Answer:
(d) Choosing process

Question 33.
The need in development of a country is :-
(a) Physical resources
(b) Economic resources
(c) Efficient management
(d) All of these
Answer:
(d) All of these

Question 34
14 principles of management is propounded by :
(a) Henary Feyol
(b) F. W. Taylor
(c) Peter Drucker
(d) A. H. Maslo
Answer:
(a) Henary Feyol

Question 35.
Liberalisation policy in India has been :-
(a) Successful
(b) Unsuccessful
(c) Normal
(d) None of these
Answer:
(a) Successful

Question 36.
Planning is helpful to :-
(a) Achieving objectives
(b) In co-ordination
(c) Effective controlling
(d) All of these
Answer:
(d) All of these

Question 37.
Wages given to workers in Traditional Management are :-
(a) Low
(b) High
(c) Normal
(d) Maximum
Answer:
(d) Maximum

Question 38.
Which of the following is not features of organization : –
(a) Group of Individuals
(b) Group of Machine
(c) A Structure
(d) A process
Answer:
(b) Group of Machine

Question 39.
Objective of employee’s development is :-
(a) Increase in knowledge
(b) Better performance
(c) opportunity of promotions
(d) All of these
Answer:
(d) All of these

Question 40.
Which of the following is not external sources of recruitment: –
(a) Transfer of employees
(b) Direct recruitment
(c) Campus recuitment
(d) Contractual recruitment
Answer:
(a) Transfer of employees

Question 41.
Type of communication are :-
(a) Written
(b) verbal
(c) Formal
(d) All of these
Answer:
(c) Formal

Question 42.
The leader possess :-
(a) Intelligence
(b) Foresightness
(c) Self-confidence
(d) Ail of these
Answer:
(d) Ail of these

Question 43.
In- effective communication language should not be :-
(a) Express
(b) Impressive
(c) Ambiguous
(d) Courtesy
Answer:
(d) Courtesy

Question 44.
Control is by employees.
(a) Opposed
(b) Supported
(c) Liked
(d) None of these
Answer:
(a) Opposed

Question 45.
The sources of working capital are :-
(a) Debtors
(b) Bank overdraft
(c) Cash sales
(d) All of these
Answer:
(a) Debtors

Question 46.
Capital market deals in
(a) Short term funds
(b) Medium term funds
(c) Long term funds
(d) None of these
Answer:
(c) Long term funds

Question 47.
Financial manager takes decision as to
(a) Finance
(b) Investment
(c) Dividend
(d) All of above
Answer:
(d) All of above

Question 48.
Consumer Protection Act was passed
(a) In 1886
(b) In 1986
(c) In 1996
(d) In 1997
Answer:
(b) In 1986

Question 49.
In India, entrepreneurial development programmer has been
(a) Successful
(b) Unsuccessful
(c) Need of improvement
(d) None of these
Answer:
(c) Need of improvement

Question 50.
Importance of Marketing concept is for
(a) Society
(b) Consumers
(c) Producers
(d) All of above
Answer:
(d) All of above

Non-Objective Type Questions

Short Answer Type Questions

Question no. 1 to 25 are Short answer type questions. Answer any 15 out of them. Each question carries 2 marks. (15 x 3 = 30)

Question 1.
Write the name of the level of manage-ment.
Answer:
Following are the level of management :

1. Top Level Management
2. Middle Level Management
3. Lower Level Management.

Question 2.
Write any three points of the nautre of principles of management.
Answer:
Management of Principles : These are the statement of fundamental truth based on creation and systematic analysis which provides guidlines for managerial decision making and action.
Nature and charecteristics of management Principles are the same which are following :

1. Flexibility
2. Univarsal application
3. lack of humanimity
4. Beharourial.

Question 3.
Write the name of any four factors of business environment.
Answer:
Principles of Management :

1. Division of work : This means assigning the work to a person for which he is best suited. This principle is equally applicable to all hands of work managerial as well as technical.
2. Unity of command : This means that sub-ordinates should be receive orders from one senior only. A sub-ordinate receiving orders from two or more bosses can satisfy none.
3. Dicipline : Disciplines mean the observance of rules and regulations this principle emphasises the obedience on the part of the sub-ordinates.

Question 4.
Write name of any four merits of scientific management.
Answer:
Following are the merit of scientific management :

1. Reduction in the cost of production.
2. Better quality products.
3. Benefits of division of labour.
4. Avoidance of disputes between labour and management.

Question 5.
State any two types of planning on the basis of level of management.
Answer:
Types of planning on the basis of level of management are discussed below :

1. Operational plan
2. Tactical plan.
3. Strategical plan

Question 6.
State any four points of importance of organization.
Answer:
Importance of organisation are discussed below :

1. Makes the management simple and efficient.
2. Encourage specilization.
3. Improves constructive tainking.
4. Increase productivity.

Question 7.
Write the name of any five advantage of organization in business.
Answer:
Advantages of organisation are following :

1. Specilization
2. Role clarity
3. Clarifies authority and responsibility.
4. Avoiding duplication of work.
5. Co-ordination.

Question 8.
State any three qualities of a good leader.
Answer:
Qualities of a good leader are mention below:

1. Physical features
2. Knowledge
3. Integrity
4. Communication skills.
5. Motivation skills.
6. Initiative
7. Self confidence
8. Decisiveness
9. Social skills.

Question 9.
State name of any two methods of ‘on-the- job training.
Answer:
Following are the two methods of “on job training”.

1. Internship training method.
2. Case study method.

Question 10.
State any three barriers of. communication.
Answer:
Effective communication is essential for effective and efficient management of an organisation.
There are a number of barriers to effective communications,
such as :

1. Semantic barriers,
2. Psychological or Emotional barriers,
3. Organisational barriers
4. Personal barriers.

Question 11.
State any two headings of the importance of supervision.
Answer:
Following are the two importance of supervision :

1. Optimum utilization of Resoures : Supervision develops work skills which help in optimum utilization of resources.
2. Controlling performance : Supervision insures performance of work as per the targets.
   Supervisior assumes responsibility for the accomplish ment of task. Undertaken and motivates his fellow workers.

Question 12.
Write any four headings of the importance of control in management.
Answer:
Following are the four heading of importance of control in management :

1. Control is basis of planning.
2. Facilitates decision making.
3. Helps in improving efficiency.
4. Appraisal of performance.

Question 13.
Write name of any three methods/ techniques of control.
Answer:
Following are the methods/Techniques of control :

1. Budgetary control.
2. Break-even analysis.
3. Statistical Data.
4. Special reports and Analysis.
5. Operational Audit or Internal Audit.
6. Personal Observation.
7. Policies, Procedures and Instructions.
8. Ratio Analysis.
9. Other Techniques.

Question 14.
Write the name of any three financial decisions taken by management.
Answer:
The three main financial decision which are generally taken by a finance manager are as under.,

1. Investment Decision.
2. Financial Decision.
3. Dividend decision.

Question 15.
Write the name of any four factors which include in capital structure.
Answer:
Following are the four factors which include in capital structure :

1. Position of cash flow.
2. Cost of capital.
3. Return on investment.
4. Risk consideration.

Question 16.
Name the two factors affecting capital structure.
Answer:
Following are the two factors affecting capital structure.

1. Cost of capital.
2. Risk consideration.

Question 17.
State any four functions of financial market.
Answer:
Following are the four important functions of financial market :

1. Mobilisation of savings and channelising them into most productive uses.
2. Informational role for price recovery.
3.  Providing liquidity to financial assets.
4. Reducing the cost of transactions.

Question 18.
Write the two headings of the function of SEBI.
Answer:
Following are the two heading of SEBI functions :

1. Protective functinsz.
2. Development functions.

Question 19.
Name any four media of advertisement.
Answer:
Following are the four medium of advertising:

1. Newspapers
2. Magazines
3. Television
4. Radio.

Question 20.
State any two characteristics of a good brand.
Answer:
Following are the two features of good brand :

1. It should be distinctive.
2. It should be appropreate.

Question 21.
State any two objectives of consumer protection programme.
Answer:
The main two objectives of consumer protection act are as below :

1. To ensure fair, competitive and responsible markets that work well for consumers and promote ethical business practice.
2. To promote and protect the economics interests of consumers.

Question 22.
State any two characteristics of entrepreneurship.
Answer:

1. Innovation : Any innovative work is entrepreneurship. New resources, new products, new technology, new utilities, new managerial skills etc., come in the perview of entrepreneurship. Thus, the basic feature of entrepreneurship is innovation.
2. A high achievement function : Achievement orientation is the most important factor for explaining economic behaviour. ‘Doing things in a new and a better way’ and ‘decision-making under uncertainty’, can be regarded as two important features of entrepreneurship.

Question 23.
Name the needs which should be satisfied first.
Answer:
Following are five basic needs which should be satisfied first.

1. Physological needs.
2. Safety needs.
3. Love and belongingness needs.
4. Esteem needs.
5. Self actualization needs.

Question 24.
Write any three merits of advertising.
Answer:
Following are the merits of Advertising :

1. Introduces new product in the market.
2. Expansion of the market.
3. Increased sales.
4. Fight competition.
5. Enhance goodwill.
6. Elimination of middlemen.
7. Better quality products.
8. Educate the consumers.

Question 25.
Name any three sourcess of raising fixed capital.
Answer:
Following are the three sources of raising fixed capital :

1. Issue of equity and preference shares.
2. Issue of Debentures.
3. Issue of Right shares.
4. Retained Earning.

Long Answer Type Questions

Question no. 26 to 33 are Long answer type questions. Answer any 4 of them. Each question carries 5 marks. (4 x 5 = 20)

Question 26.
What is divisional organization ? State its main characteristics.
Answer:
Divisional Organisation/Departmentation: A department is a work group or unit which is created for performing certain functions of .similar nature. The process of division of the enterprise into different parts is broadly called departmentation.

The various parts or divisions are called as departments. It leads to grouping of both functions and personnel who are assigned to carry out allocated functions. It helps in creating a sound organisation structure. There can be many methods of departmentation. Every enterprise choose the appropriate basis or method depending upon its objectives, size, etc.

Merits :

1. This arrangement makes effective control possible
2. This arrangement is based on the principle of specialisation
3. It estrablishes co-ordination on the departmental level.

Demerits :

1. The weakness of one department affects the other departments
2. All the departments function according to their sweet will making inter-departmental co-ordination difficult
3. This system is q hurdle in the way of the complete development of the employees.

Question 27.
Explain the importance of decentralization.
Answer:
Decentralisation refers to the systematic effort to delegate to the lowest level all authority except which can be exercised at the central point.

The following factors highlight its importance :

1. Greatern Motivation : Decentralisation improves the morale and motivation of Subordinates which is reflected in better work performance.
2. Develops initiative among subordinates : Decentralisation helps to promote self-reliance and confidence amongst the subordinates. This is because when lower managerial levels are given freedom to take their own decisions, they learn to depend on their own judgement. It helps to promote initiative and creativity among them.
3. Develops managerial talent for the future : As a result of decentralisation, employees get more opportunities to develop new skills. It makes them better future managers.
4. Quick decision making : Decentralisation in an organisation, provides more freedom to lower level managers to take their own decisions. There is no need to get approval from higher level. It helps in quick and better decision making.
5. Facilitates growth and expansion : Decentralisation facilitates organisational growth through expansion and diversification.

Question 28.
Explain in brief the various methods of training.
Answer:
There are various methods of training. These are broadly categories into two groups :

• On the job.
• off-the job methods.

On the job methods :

1. Apprenticeship programmes: Apprenticeship programmes put the trainee under the guidance of master worker. These are designed to acquire a higher level of skill.
2. Coaching : In this method, the superior guides and instructs the trainee as a coach. The coach or counseler sets mutually agreed upon goals.
3. Internship training : It is a joint programme of training in which educational instigutions and business firms cooperate.
4. Job rotation : This kind of training involves shifiting the trainee from one department to another of from or one job to another.

Off the job methods:

1. Class room lectures/conferences: The lecture or conference approach is well adapted to conveying specific information rules, procedures or methods.
2. Films : They can provide information and explicitly demonstrate skills that are not easily represened by the other techniques.
3. Case study : Taken from actual experiences of organisations, cases represent attempts to describe,
   as accruetly as possible real problems that managers have faced.
4. Computer modelling: It simulates the work environment by programming a computer to imitate some of the realities of the job and allows learning to take place without the risk or high costs.
5. Vestibule training : Employees learn their jobs on the equipment they will be using, but the training is conducted away from the actual work floor.
6. Programmed instruction : The method incorporates a prearranged and proposed acuisition of some specific skills or general knowledge.

Question 29.
Discuss the importance of directing.
Answer:
Following are the importance of Directing :

1. Managerial function : Directing is a managerial function. It is through directing, the managers guides, inspires and leads the employees to perform the task assigned.
2. Continuing function : Directing is a continuous function. The managers continuously guide, inspire and lead the employees to get the work done.
3. Integrating process : Directing is an integrating process. It integrates the efforts of the employees to achieve the organisational objectives. It provides direction to their efforts. In the absence of direction, their efforts may not focus or concentrate on the objectives of the organisation and may remain inactive.
4. Pervasive function : Directing is a responsibility of all managers. It is performed at all levels of the organisation. Directing flow from top to lower levels of management.
5. Creative function : Driecting is a creative function. It converts paper plans into reality by initiating, guiding, leading and supervising.

Question 30.
Explain any four needs that motivate an employee to work.
Answer:
Froms of Non-financial Incentives: In order to motivate the employees management may use the following forms of non-financial incentives :

(i) Praise of appreciation of work done : Recognition of satisfactory performance acts as non- financial incentive since it satisfies one’s ego needs. However, this incentive should be used with great care because praising an incompetent employee creates resentment among competent employees.

(ii) Workers’ participation in management : Participation in management provides strong motivation to the employees. Gives them psychological satisfaction if there voice is header participants in management provides for two ways communication and so imbibes a sense of importance.

(iii) Suggestion system : Suggestion system is an incentive with satisfies many needs of the employees. Many organisations which use the suggestion system make use of cash awards for useful suggestion. They sometimes publish the workers name with the photograph in the company magazine. This motivates the employees to be in search for something which may be of greater use to the organisation.

(iv) Competition : If there is healthy competition among individual employees, group of employees, it leads them to achieve their persoanl or group goals. Hence, competition acts as none financial incentives.

(v) Opportunity for growth : Opportunity for growth is another kind of intensive. If the employees are provide opportunity for their advertisement and growth to develop their personality, they feel very much satisfied and more communicate to organisation goals.

Question 31.
Explain the functions of financial manager.
Answer:
Finances are the cornerstone of every business. The prime goal of my organization would be to garner huge profits and this is only possibe withh proper management of the finance. Therefore, effectual finance Management is imperative for every organization as it leads to enhanced profits are reduction in the operational cost.

A finance manger plays an impoertant role in the mangement of a business organbization as he manges all the activites related to finance. There are many functions that a financial manager is expected to perform .
These include.

1. Estimating the amount of capital required for the proper functioning of the business : The most basic function of a finance manager is the estimation of the capital because funds are required for both long term and short term. The firm requires capital so that it can its liability with no delay, benefit from early business opportunites, pay for resources, op-erational cost etc.

2. Devising a capital structure : For the determining the capital structure, the finance manager must ensure that the earning rate is higher than the rate of interest on the borrowed amount.

3. Sources to raise funds : For proper financial management, it is imperative to find can raise funds. The organisatiion can raise funds through different sources including equity and preference shares, debentures, banks, financial institutions other souces.

4. Acquisition of funds : While acquiring funds, the financial manager needs to follow some basic step such as legal formalities and documentation’ required.

Question 32.
What is working capital ? How is it calculated ?
Answer:
Meaning of Working Capital : Working capital refers to that capital which is utilized for meeting current liabilities by cash payments in the ordinary course of business. In other words, the working capital is invested in raw materials, in stock of partly finished goods in meeting day-to-day or current exenditure on salaries, wages, rent, rates, taxes, insurance, advertisement etc. in cash.
Determinants of Working Capital
(1) Size of Business : Larger of the business enterprise, greater would be the need for working capital. The size of a business may be measured in terms of scale of its business operations.

(2) Production Cycle : Production cycle means the time-span between the purchase of raw materials and its conversion into finished goods. The longer the production cycle, the larger will be the need for working capital.

(3) Production Policy : The need for working capital is also determined by production policy. The demand for certain products (such as woolen garments) is seasonal. Two type of production policies may be adopted for such products.

(4) Availability of Raw Material : If the raw material required by the firm is available easily on a continuous basis, there will be no need to keep a large inventory of such materials and hence the requirement of working capital will be less. On the other hand, if the supply of raw material is irregular, the firm will be compelled to keep an excessive inventory of such materials which will result in high level of working capital.

(5) Availability of Credit from Banks :If a firm can get easy bank credit facility in case of need, it will operate with less working capital

Question 33.
Explain any five functions of marketing.
Answer:
Function of Marketing:
(i) Gatrhering and analysing market information : An important function of a marketer is gather and analyse market information. It is necessary to identify the needs the customers and to take various decisions for the successful marketing of the products and services.

(ii) Marketing planning : Marketing manager has to develop appropriate marketing plans to achieve the marketing objectives of the firm.

(iii) Customers support services : Another very important function of marketing management relates to developing customers support serves such as procuring credit service after sales services, handling customer complaints, maintenance services, technical services and consumer information. All these services aim at providing maximum satisfaction to the customers.

(iv) Physical distributions : A very important function of marketing is to arrange for distribution o f goods and services. Physical distribution includes decisions regarding choice of channels of distribution, maintaining inventory, storange, warehousing etc.

(v) Utilising funds : It is the task of the finance manager to ensune that the funds are inuested wisely so as to garner maximum roll.

(vi) Disposing of Profits : Effectcial finance management involves Inalysing the funds that can be invested for proper working of the organization and distributing the rest amoung the shareholders.

(vii) A financial manager needs to manage the cash in such a way that there its neither shortage nor surplus and decily expenses can be met without any hassles.

(viii) Finance Management involves avaluation and control of the financial perform once of an organization

Bihar Board 12th Economics Model Papers

Bihar Board 12th Economics Model Question Paper 5 in English Medium

Time : 3 Hour. 15 Min
Full Marks : 100

Instructions

1. Candidates are required to give their answers in their own words as far as practicable.
2. Figures in the right hand margin indicate full marks.
3. 15 minutes of extra time has been allotted for the candidate to read the questions carefully.
4. This question paper has two sections : Section-A and Section-B.
5. In Section-A, there are 50 objective type questions which are compulsory, each carrying 1 mark. Darken the circle with black/blue ball pen against the correct option on OMR Sheet provided to you Do. not use Whitener/Liquid/Blade/Nail on OMR Sheet, otherwise the result will be treated as invalid.
6. In Section-B, there are Non-objective type questions. There are 25 Short answer type questions, out of which any 15 questions are to be answered. Each question carries 2 marks. Apart froms this, there are 08 Long answer type questions, out-of which any 04 of them are to be answered. Each questions carries 5 marks.
7. Use of any electronic device is prohibited.

Objective Type Questions

Question No. -1 to 50 have four options provided, out of which only one is correct. You have to mark, your selected option, on the OMR-Sheet. Each questiion carries 1 (one) mark. [50 x 1 = 50]

Question 1.
Which is a central problem of an economy ?
(a) Allocation of Resources
(b) Optimum utilization of Resources
(c) Economic development
(d) All of these
Answer:
(d) All of these

Question 2.
Which of the following is a source of production ?
(a) Land
(b) Labour
(c) Capital
(d) All of these
Answer:
(d) All of these

Question 3.
According to whom, Economics is a science of human welfare ?
(a) A. Marshall
(b) Paul Samuelson
(c) J.S.Mill
(d) Adam Smith.
Answer:
(a) A. Marshall

Question 4.
Which of the following is not a factor of production ?
(a) Land
(b) Labour
(c) Money
(d) Capital
Answer:
(c) Money

Question 5.
The word ‘micro’ was first used by __________
(a) Marshall
(b) Boulding
(c) keynes
(d) Ragnar Frisch
Answer:
(d) Ragnar Frisch

Question 6.
Consumer’s behaviour is studied in __________
(a) Micro-economics
(b) Income theory
(c) Macro-economics
(d) None of these
Answer:
(a) Micro-economics

Question 7.
Elasticity of demand for necessary goods is __________
(a) zero
(b) unlimited
(c) greater than unity
(d) less than unity
Answer:
(a) zero

Question 8.
Which of the following factors affects elasticity of demand ?
(a) Nature of goods
(b) Price level
(c) Income level
(d) All of these
Answer:
(d) All of these

Question 9.
Law of demand is a __________
(a) Qualitative statement
(b) Quantitative statement
(c) Both (a) and (b)
(d) None of these
Answer:
(c) Both (a) and (b)

Question 10.
In production function, production is a function of __________
(a) price
(b) factors of production
(c) total expenditure
(d) None of these
Answer:
(b) factors of production

Question 11.
At which time all the factors of production may be changed ?
(a) Short run
(b) Long run
(c) Very long run
(d) All of these
Answer:
(a) Short run

Question 12.
Average variable costs can be defined as __________
(a) TVC x Q
(b) TVC + Q
(c) TVC – Q
(d) TVC -r Q
Answer:
(d) TVC -r Q

Question 13.
For a firm’s equlibrium __________
(a) MR = MC
(b) MR > MC
(c) MR < MC
(d) MR = MC = 0
Answer:
(a) MR = MC

Question 14.
Supply is associated with __________
(a) a time period
(b) price
(c) both (a) and (b)
(d) none of these
Answer:
(c) both (a) and (b)

Question 15.
Determining factor of supply of goods is __________
(a) Price of goods
(b) Price of related goods
(c) Price of factors of production
(d) All of these
Answer:
(d) All of these

Question 16.
Which is a characteristic of the market ?
(a) One area
(b) Presence of Buyers and” Sellers
(c) Single price of the commodity
(d) All of these
Answer:
(d) All of these

Question 17.
Which one is a feature of monoplistic competition ?
(a) Differentiated product
(b) Selling cost
(c) Imperfect knowledge of the market
(d) All of these
Answer:
(d) All of these

Question 18.
Which is a reason of change in demand ?
(a) Change in Consumer’s Income
(b) Change in price of related goods
(c) Population increase
(d) All of these
Answer:
(d) All of these

Question 19.
Net National Income at factor cost is called __________
(a) National Income
(b) Gross Investment
(c) Income
(d) None of these
Answer:
(a) National Income

Question 20.
Depreciation expenses are included in __________
(a) GNPMP
(b) NNPMP
(c) NNPpc
(d) none of these
Answer:
(a) GNPMP

Question 21.
Which one is included in three sector model ?
(a) Family
(b) Goverment
(c) Firm
(d) None of these
Answer:
(b) Goverment

Question 22.
Which service is included in Tertiary sector ?
(a) Mining
(b) Construction
(c) Communication
(d) Animal Husbandry.
Answer:
(d) Animal Husbandry.

Question 23.
Which method is adopted in measuring National Income ?
(a) Production method
(b) Income method
(c) Expenditure method
(d) All of these
Answer:
(d) All of these

Question 24.
“Money is what money does”- Who said it ?
(a) Hawtrey
(b) Keynes
(c) Hartley Withers
(d) Prof. Tinbergen
Answer:
(c) Hartley Withers

Question 25.
Which is the primary function of commercial banks ?
(a) Accepting deposits
(b) Advancing loans
(c) Credit creation
(d) All of these
Answer:
(d) All of these

Question 26.
The full form of ATM is __________
(a) Any Time Money
(b) All Time Money
(c) Automated Teller Machine
(d) both (a) and (b)
Answer:
(c) Automated Teller Machine

Question 27.
Reserve Bank of India was established in __________
(a) 1947
(b) 1935
(c) 1937
(d) 1945
Answer:
(b) 1935

Question 28.
Micros which means ‘small’ belongs to which language ?
(a) Arabic
(b) Greek
(c) German
(d) English
Answer:
(b) Greek

Question 29.
How many types of elasticity of demand is there ?
(a) Three
(b) Five
(c) Six
(d) Seven
Answer:
(b) Five

Question 30.
Which money is issued by the central bank ?
(a) Currency
(b) Credit money
(c) Coins
(d) All of these
Answer:
(b) Credit money

Question 31.
RBI announced the guidelines to issue itences to new banks of Private Sector on __________
(a) January 22, 1993
(b) March 15,1995
(c) April 1,1999
(d) None of these
Answer:
(a) January 22, 1993

Question 32.
Banking Sector Reforms in India began in __________
(a) 1969
(b) 1981
(c) 1991
(d) 2001
Answer:
(c) 1991

Question 33.
“Supply creates its own demand” Who gave this law ?
(a) J. B. Say
(b) J.S.Mill
(c) Keynes
(d) Ricardo.
Answer:
(c) Keynes

Question 34.
On Which factor does Keyneaian theory of employment depend ?
(a) Effective demand
(b) Supply
(c) Production efficiency
(d) None of these
Answer:
(a) Effective demand

Question 35.
Who is the writer of the book. ‘Traited Economic Politique’ ?
(a) Pigou
(b) J. B. Say
(c) Keynes
(d) Ricardo
Answer:
(b) J. B. Say

Question 36.
If MPC = 0.5 then mulutiplier (k) will be __________
(a) i-
(b) 0
(C) f
(d) 2
Answer:
(d) 2

Question 37.
On which concept does classical viewpoint depend ?
(a) Say’s law of market
(b) Perfect Flexibility of wage Rate
(c) Perfect Flexibility of Interest Rate
(d) All of these
Answer:
(b) Perfect Flexibility of wage Rate

Question 38.
Which is included in indirect tax ?
(a) Income tax
(b) Wealth tax
(c) Excise duty
(d) Gift tax
Answer:
(c) Excise duty

Question 39.
Which one is the item of Current Account ?
(a) Import of visible items
(b) Expenses of tourists
(c) Export of visible items
(d) All of these
Answer:
(d) All of these

Question 40.
Balance of trade means __________
(a) capital transaction
(b) import & export of goods
(c) total debit and credit
(d) all of these
Answer:
(d) all of these

Question 41.
What is price flexibility of a necessities of demanded things ?
(a) Zero
(b) Infinite
(c) More then a unit
(d) less than unit
Answer:
(a) Zero

Question 42.
‘Profit is the award of bearance risk’ who said this ?
(a) Halley
(b) J. B. Clark
(c) Knight
(d) None of these
Answer:
(c) Knight

Question 43.
The market situation in which there is only are consumer is called __________
(a) Monopoly
(b) Monopsani
(c) Duopoly
(d) None of these
Answer:
(c) Duopoly

Question 44.
On which matter it is decide of general value, __________
(a) market day
(b) short-term market
(c) long term market
(d) none of these
Answer:
(b) short-term market

Question 45.
Following is not a source of origin __________
(a) Land
(b) Labour
(c) Money
(d) Capital
Answer:
(c) Money

Question 46.
Who the Central Bank of India ?
(a) SBI
(b) Central Bank of India
(c) Reserve Bank of india
(d) None of these
Answer:
(c) Reserve Bank of india

Question 47.
When was establish Reserve Bank of India ?
(a) In 1932
(b) In 1935
(c) In 1945
(d) In 1956
Answer:
(b) In 1935

Question 48.
In which year the nationalisation of the commercial bank:
(a) 1960
(b) 1968
(c) 1969
(d) 1980
Answer:
(c) 1969

Question 49.
Central Bank can control by which __________
(a) Bank Rate
(b) Open market
(c) CRR
(d) All these
Answer:
(d) All these

Question 50.
When was establish State Bank of India ?
(a) 1950
(b) 1955
(c) 1960
(d) 1965
Answer:
(b) 1955

Non-Objective Type Questions

Short Answer Type Questions

Question no. 1 to 25 are Short answer type questions. Answer any 15 out of them. Each question carries 2 marks. (15 x 3 = 30)

Question 1.
State any four difficulties of Barter System.
Answer:
The four difficulties of Barter system are as follows:

1. Lack of Double Coincidence : The barter system requires a double coincidence of wants on the part of those who want to exchange goods or services. lt is necessary for a person who wishes to trade his goods or service to find some other person who is not willing to buy his goods or service,but also possesses that goods which the former wants.
2. Difficulties in store value : A major difficulty in barter system appears because store of purchasing power for future can not be made due to perishable nature of most of the goods.
3. Lack of common acceptability unit of value : Due to lack of common acceptable unit of value ,it becomes difficult to determine.The value of commodity to be exchanged.
4. Lack of divisibility in commodities: Another difficulty of barter system relates to the fact that all commodities can not be divided or sub-divided.

Question 2.
What is law of supply ? Explain it with illustration.
Answer:
The law of supply states, that other things remaining constant, the higher the price, the greater the quantity supplied or the lower the price, the smaller the quantity supplied.Law of supply states the positive relationship between price of the commodity and its supply.Producer always wants to sell his commodity at a higher price and less at a lower price .Thus,price of commodity and its supply are positively related.In functional form.S = f (P) Where S refers to supply of the commodity and P for price.Thus,supply function of a commodity represents a direct relationship between supply of commodity and its price.

The law of supply can also be explained with ‘Supply schedule’ and ‘Supply Curve.

Above table shows individual supply schedule, that explains supply of commodity increases with increase in price.

Question 3.
Discuss the main features of government budget.
Answer:
The main features of Government budget are as follows:

1. Encouragement to economic development: The basic objective of the budget is to accelerate the pace of economic development in the country.For accelerating the pace of economic development:
   • government may grant tax rebates to productive activities
   • government may develop infrastructure like roads .bridges etc.
   • government may establish public enterprises.
2. Balanced Regional Development : Through budget .government may promote the development in backward areas for ensuring balanced regional development in the economy. Engorgement may grant tax rebates to these areas,may establish public enterprises in these areas and may allocate more funds for infrastructural development in these backward areas.
3.  Re- distribution of income and property : Budget plays a vital role in reducing the economic disparities in the economy.Many steps can be taken in the budget for reducing the economic disparities in the economy.
4. Economic Stability: Economy faces the cycles of boom and depression and the budget aims to put a control on these cycles.
5. Creation of employment : Employment creation is one of the important objectives of government budget.Govemment may promote labour – intensive techniques in public works programmes and may also initiate programmes in the economy.

Question 4.
Distinguish between primary sector and secondary sector.
Answer:
Difference between Primary sector and secondary sector are as follows :
Primary sector :

1. It is that sector which exploits natural resources and produce goods and services.
2. It is known as agriculture and allied sector.
3. It includes all agricultural and allied activities such as forestry,mining,quarrying,fishing,animal husbandry etc.
4. Unorganised and traditional techniques.
5. No possibility of division of labour.

Secondry sector :

1. It is that sector which transforms one goods into another for creating more utility from it.
2. Famously known as manufacturing sector.
3. It includes manufacturing units small scale units, large firms ,big corporate, multinational corporation.
4. Organised techniques.
5. Complex division of labour can be used for production.

Question 5.
What is National Income ?
Answer:
National income is the sum of factor incomes earned by normal residents of a country during the period of one year.

NY = National income
Z = Sum or total (Z is called sigma)
FY = Factor income
n = all normal residents of a country.
Rent, interest, profit and wages are the factor incomes. So, national income is the sum of rent, interest, profit and wages earned by normal residents of a country during an accounting year.

According to the central statistical organisation (the official agency engaged in the estimation of national income in India) defines national income as under: “National income is the sum of factor income earned by the normal residents of a country in the form of wages, rent, interest and profit in an accounting year.”

Question 6.
Define the functions of Central Bank.
Answer:
Principal function of the central bank are as follows :

1. Issuing of notes : In modem times, central bank alone has the exclusive right to issue notes in every country of the world. The notes, issued by the central bank are unlimited legal tender throughout the country. Central bank of the country enjoys monopoly right of note issuing.
2. Banker to the Government: Central bank acts as a banker, agent and financial advisor to the government. As a banker to the government, it keeps the accounts of all government banks and manages government treasuries. It performs the some functions for the government as the commercial banks do for their customers.
3. Banker’s bank : It performs the function of a banker to all other banks in the country. Central bank has almost the same relation with all other banks as a commercial bank has with its customers. It keeps part of the cash balances of all commercial banks as deposit with a view to meeting liabilities of these banks in times of crisis.
4. Supervision of the banks : As a banker’s bank, the central bank also supervises the commercial banks.
   The supervision of commercial banks relates to
   • licensing of the commercial banks
   • expansion of the commercial banks in terms of their branches across different parts of the country.
5. Lender of the last resort : The central bank also acts as lender of last resort for the other banks of the country. It means that if a commercial bank fails to get financial accommodation form anywhere, it approaches, the central bank as a last resort.

Question 7.
Explain law of demand.
Answer
The law of demand stages that, other things being equal the demand for a good extends with a decrease in price and contracts with an increase in price. There is inverse relationship between quantity demanded of a commodity and its price, provided other factors influencing demand remain unchanged.

The law of demand states that other things remaining constant, quantity demanded of a commodity increases, with a fall,in price and diminishes when price increases.

Question 8.
What do you mean by Macro-economics ?
Answer:
The term Macro in English has its origin in the Greek term Macros which means large. In the context of macro economics “large” means economy as a whole. Thus, macro economic is defined as that branch of economics which studies economic activities at the level of an economy as a whole.

According to M. H. Spencer, “Macro-economics is concerned with the economy as a whole or large segments of it. In Macroeconomics, attention is focused on such problems as the level of unemployment, the rate of inflation, the nation’s total output and other matters of economy-wide significance.”

Question 9.
Explain the functions of money.
Answer:
Functions of money are classified into following two categories:

1. Primary or main functions,
2. Secondary or subsidiary functions.

1. Primary or main functions : This category includes those functions of money, which are common to all countries during all periods.

• Medium of exchange : Medium of exchange is an important function of money. It means that money acts as an intermediary for the goods and services in the exchange transaction. The medium of exchange function of money has classified all transactions on the basis of time and place.
• Measure of value or unit.of value : Unit of account means that the value of each good as service is measured in the monetary unit. Money measures the value of everything or the prices of all goods and services can be expressed in terms of money.

2. Secondary Functions : These functions are supplementary to primary functions. These are as follow.

• Standard of Deferred Payment : Deferred payment means those payments which are to be made in futuse.
• Store of Value : Human beings has a tendancy to save a part of his income for future to fulfil his future requirements. Store of value can take place only when person becomes confident to use his saving as per his requirements in future.
• Transfer of Value : Money is a licuid means of exchange. Hence, purchasing power of money can easirly be transferred from one person to another or one place to the other. Thus, in modem times, money has become the best means of tranferring the value of money.

Question 10.
Write the sources of production.
Answer:
There are five types of the factor of production :

1. Land
2. Labour
3. Capital
4. Organisation
5. Enterprise.

Land, labour, capital, machines tools, equipments and natural means are limited. Every demand of every individual in the economy cannot be satisfied, so the society has to decide what commodieits are to be produced and to what extent. Goods purchased in an economy can be classofied as consumer goods and produce goods. These goods may be further classified as single use goods and durable goods.

It is undoubtedly the basic problem of the economy. If we produce one commodity, it will mean that we are neglecting the production of the other commodity. We assume that all the factors of production in the economy are fully absorbed, so if we want to increase the production of one commodity, we will have to withdraw resources from the production of the other commodity on the basis of 4 requirements goods are further classified as goods for necessaries comforts and luxuries.

Question 11.
Write the Functions of money.
Answer:
Primary function of money are also called prime functions. These functions are of prime importance and common to all countries during all the periods. Money has two primary functions.

1. Medium of exchange : Money acts as a medium of exchange. In modem days, exchange is the basis of entire economy and money makes this exchange possible. At old age barter system was in practise in which goods were exchanged for goods but due to lack of double co¬incidence exchange was difficult. But the uses of money has removed this difficulty. In modem times, money performs all function of exchange in the economy.
2. Measure of value : Money acts unit of measure of value. In other words it acts as a yardstick of standard measures of value to which all other things can be measured. In barter system the general measurement of value was absent and consequently it was difficult to measure the value of exchange. In modem times, the value of every commodity can be measured in money, with the use of money, economic calculations for measuring values have become simplified

Question 12.
What do you mean by NNP ?
Answer:
Net National product at factor cost (NNP_FC) is the sum of total factor income (rent + interest + profit + wages) genrated within the domestic territory of a country along with net factor income from abroad during a year. NNP is the sum of total factor incomes earned.by normal residents of a country during a year.
NDP_FC + Net factor income from abroad = NNP_FC

Question 13.
Explain the importances of Government Budget.
Answer:
The notable objective and importance of government budgets are as follows :

1. Redistribution of income and wealth: Equitable distribution of income and wealth is a sign of social justice which is the principal objective of any welfare state as in India.
2. Reallocation of resources : The government of a country directs the allocation of resources in a manner such that there is a balance between the goals, of profit maximization and social welfare.
3. Economic stability : These refer to the phases of recession, depression, recovery and boom in the economy. Budget is used as an important policy instrument to combat the situations of deflation and inflation. By doing it the government tries to achieve the state of economic stability.
4. Managing public enterprises : The budgetary policy of the government shows interest of the government to increase the rate of growth through public enterprises.

Question 14.
Explain the merits or advantages of perfect competition.
Answer:
The following are the main advantages of. perfect competition:

1. Large number of firms or sellers : The number of firms selling a particular commodity is so large that any increae or decrease in the supply of one particular firm hardly influences the total market supply.
2. Large number of buyers : Not only is the number of sellers very large, also, the number of buyers is very large. Accordingly, like an individual firm, an individual buyer is also not able to influence price of the commodity. Accordingly an individual buyer under perfect competition is also a price taker.
3. Homogeneous product : All sellers sell identical units of a given product. Seeling homogeneous product at the given price rules out the possibility of advertisement or other sale-promotion expenses. So, that there are selling costs, in perfectly competitive market.
4. Perfect knowledge : Buyers and sellers are fully aware of the price prevailing in the market. Buyers know it fully well at what price sellers are selling a given product.
5. Free entry and exit of firms : A firm can enter and leave any industry. There is no legal restriction on the entry or exits.
6. Perfect mobility : Factors, of production are perfectly mobile under perfect competition.

Question 15.
What is GDP ?
Answer:
Gross Domestic Product (GDP) is the market value of the final goods and services produced during a year within the domestic territory of a country.

GDP is the market value of the final goods and services produced within the domestic territory of a country during one year inclusive of depreciation. There are both resident as well as foreign producers within the domestic territory of a country. In India, for example, there are many international banks as well as multinational companies. Gross domestic product includes the market value of the final goods and services produced by all such producers.

Question 16.
Explain the four difficulties of barter exchange.
Answer:
The four difficulties of barter exchange are as follows:

1. Lack of double coincedence : The barter system requires a double coincidence of wants on the parts of those who want to exchange goods or services. It is necessary for a person who wishes to trade his goods or services. It is necessary for a person who wishes to trade his goods or services, but also possesses that goods which the farmer wants.
2. Difficulties in store of value: A major difficulty in barter system appears because store of purchasing power for future can not be made due to perishable nature of most of the goods.
3. Lack of common acceptability unit of value :
   Due to lack of common acceptable unit of value, it becomes difficult to determine. The value of commodity to be exchange for example how will it be determined that how much wheat will be exchanged for are metre of cloth and vice versa.
4. Lack of divisibility in commodities : Another difficulty of barter system relates to the fact that all commodities can not be divided or sub-divided. If the commodity is divided, its utility is lost.

Question 17.
What is law of supply ?
Answer:
The law of supply states that other things remaining constant, quantity supplied of a commodity increases with increase in the price and decreases with a fall in its price.

Law of supply states that, other things remaining constant, there is a positive relationship between price of a commodity and its quantity supplied. Thus, more is supplied at higher price and less at the lower price. There is positive relation between the price and quantity supplied. The law of supply only explain the extension and contraction of supply in response to increase and decrease in price of the commodity. It does not explains increase or decrease in supply.

Supply curve (SS) slopes upward and shows increases in quantity supplied in response to increase in price of the commodity. Thus, quantity supplied increases, when price rises.

Question 18.
Write the advantages of government budget.
Answer:
Advantages of government budget : Budgets plays a decision-making role in planned economy. The goals of economic development in a planned economy may be achieved with the basic instruments of budget. A budget in a planned economy may contain the following advantages.

1. In a planned economy budget is based on the broad objectives of national planning.
2. In initials phase of economic development, planning is supported by deficit budget which is brought to near balanced budget in the later stage of development.
3. In a planned economy a policy of Justice in Taxation is adopted while making budget and for it the policy of progressive taxation is adopted.
4. Budget also plays a positive role in performing the economic activities in the country.

Question 19.
Explain difference between primary and secondary sector.
Answer:
Differences between Primary and Secondary sector are as follows :
Primary Section :

1. It is that sector which exploits natural resources and produce goods and services.
2. It is known as agriculture and allied sector.
3. It includes all agricultural and allied activities such as forestry, mining, quarrying, fishing, animal husbandry etc.
4. Unorganised and traditiona techniques.
5. No possibility of division of labour.

Secondary Sector :

1. It is that sector which transforms one goods into another for creating more utility from it.
2. Famously known as manufacturing sector.
3. It includes manufacturing units, small scale units, large firms, big carporates, multinational corporation.
4. Organised techniques.
5. Complex divisin of labour can be used for production.

Question 20.
Define various types of credits in bank.
Answer:
Principal instruments of monetary policy or credit control of the central bank of a country are broadly classified as:

(a) Quantitative instruments and
(b) Qualitative instruments

(a) Quantitative instruments of monetary policy : There are those instruments of monetary policy which affect supply of money in the economy. These important of monetary policy are as follows :

• Bank rate : The bank rate is the minimum rate at which the central bank of a country (as a lender of last resort) is prepared to give credit to the commercial banks.
• Open market operations : Open market operations refer to the sale and purchase of securities in the open market by the central bank. Cash balances are high powered money on the basis the which commercial banks create credit.

(b) Qualitative Instruments of monetary policy :

• Margin Requirements : The margin requirement of loan refers to the difference between the current value of the security offered for loans and the values of loans granted.
• Rationing of credit: Rationing of credit refers to fixation of credit quotas for different business activities.

Question 21.
What is meant by limitations in Economics ?
Answer:
Economics has classified in two branches :

1. Micioecoomics
2. Macroeconomics

Limitations of Micro economic are as follows : Micro economic analysis fails to adopt the shape of “Universal Analysis” due to its various limitations are as follows:

1. Study not of whole but of a fraction : Micro economics studies only a fraction of a economy and does not study the entire economy. The entire economy can not be represented by studying only individual units.
2. Inadequate analysis : Micro economic analysis is an inadequate analysis because conclusions derived from individual units may not be applicable to entire economy.

Limitations of Macroeconomic are as follows :

1. Macro Economic Paradoxes : Sometimes aggregates provide misleading conclusions. What is true for an individual may not be true for the entire group.
2. Individual units are ignored: Macro economics puts an emphasis on the entire society while individual units, which make the society, are ignored.

Question 22.
What is the difference between Direct tax and Indirect tax.
Answer:
Distinctinction between Direct tax and Indirect tax: .

Direct Taxes :

1. The are directly paid to government by the person on whom it is imposed.
2. They are generally progressive. The rate of tax increase with increase in income.
3. They cannot be shifted on to others.

Indirect Taxes:

1. They are paid to the government by one person but their burden is borne by another person.
2. They are generally regressive. The rate of tax decreases as income increases.
3. They can be shifted on to others.

Question 23.
Explain the functions of commercial banks.
Answer:
The functions of commercial banks are as follows :

(i) Accepting deposits : The prime function of the commercial bank is to accept deposits from bank.
The various types of deposits accepted by the commercial bank are as follows :

• Current Deposits : Deposits in current account are termed as current deposits. A depositer can deposit the amount any member of times he likes and can also withdraw the amount any number of times he wants.
• Saving deposits: Such accounts generally belong to the people having small savings and who do not require withdrawal of money many times.
• Fixed deposits : In fixed accounts, account is deposited for a certain fixed period. Depositor gets deposits receipt while depositing cash in such accounts.
• Recurring deposit : Recurring deposits are certain type of fixed deposit. Depositor deposits certain amount every month in this account.

(ii) Granting loans : The second important primary function of commercial banks is advancing of loans. After keeping certain cash reserves, the banks lend their deposits to needy borrowers.
Various types of loans granted by banks are as follows :

• Cash credit : In cash credit system, bank provides, loans to the borrower against bonds or some other types of securities.
• Overdraft: Customers having current account with the bank are granted the facility of withdrawing more money than the amounts lying in their accounts.
• Loans and advances : A particular, amount is given by banks as loan and advances which is deposited in customer’s account.
• Discounting the bills of exchange : Bank discounts the bill of exchange i.e. after making some marginal deductions, the pays the value of the bill to the holder.
• Investment in government securities : Banks also grant loan to the government. The buying of government securities by banks is termed as ‘Earning to the government:’

(iii) Credit creation : In present times, credit creation has become the prime function of commercial banks. Banks invite primary deposits from the public and grant loan many times than these, priihary deposits on the basis of credit multiplier.

Question 24.
What are main advantages of balance of payments.
Answer:
The main advantages of Balance of Payment are as follows :

1. Systematic record : It is a record of payment and receipts of a country related to its import and export with other country.
2. Fixed period of time : It is amount of a fixed period of time generally a year.
3. Comprehensiveness : It includes all types of visible items invisible items and capital transfer.
4. Double entry system : Payment and receipts are accounted on the basis of double entry system.
5. Self-balanced: Double entry system itself keeps balance of payment as balanced.
6. Adjustment of differences : Whenever difference arises between total receipts and payments, this disequilibrium needs to be adjusted. Balance of payments is thus as overall record of all economic transactions of a country in a given period with rest of the world.

Question 25.
What is Demand ?
Answer:
Demand refers to the quantities of a commodity that the consumers are able and willing to buy at each possible price of the commodity during a given period of time.
The three elements of demand for a commodity :

1. desire for a commodity
2. money to fulfill that desire
3. readiness to spend money.

Thus, demand may be defined as the desire to buy a commodity, backed by sufficient purchasing power and the willingness to spend.

Long Answer Type Questions

Question no. 26 to 33 are Long answer type questions. Answer any 4 of them. Each question carries 5 marks. (4×5 = 20)

Question 26.
Explain the different functions of money.
Answer:
The different functions of money are mainly of two types :

1. Primary functions
2. Secondary functions

1. Primary functions: Primary functions of money are also called prime functions. These functions are of prime importance and common to all countries during all the periods. Money has two prime functions:

• Medium of exchange : Money acts as a
  medium of exchange.In modem days,exchange is the basis of entire economy and money makes this exchange possible.
• Measure of Value : Money acts a unit of measure of value.The value of every commodity can be measured in money.

2. Secondary functions : These functions are supplementary to primary functions.There are following three secondary functions are as follows:

• Standard of deferred payments : Deferred payments mean those payments which are to be made in future.
• Store of value : Store of value can take place only when person becomes confident to use his savings as per his requirements in future.
• Transfer of value : Money is a liquid means of exchange. Hence, purchasing power of money can easily be transferred from one person to another or one place to the other.

Question 27.
Discuss the characteristics of Perfect Competition.
Answer:
Perfect competition.is that market situation in which a large number of buyers and sellers are found for homogeneous product single buyer or the seller are not capable of affecting the prevailing price and hence in a perfect competition market, a single market price prevails for the commodity.
Features of Perfect Competition :

1. Large number of buyers and sellers : Perfect competition market has a large number of buyers and sellers and hence any buyer or seller can not influence the market price. In other words individual buyer or seller can not influence the demand and supply conditions of the market.
2. Homogeneous product: The units sold in the market by all sellers are homogeneous (or identical) in nature.
3. Free entry and exit of firms : In perfect competition any new firm may join the industry or any old firm may quit the industry. Hence there is no restriction on free entry or exit of firms into/from the industry.
4. Perfect knowledge of the market: In perfect competition every buyer has the perfect knowledge of market conditions. None of the buyers will buy the commodity at higher price than the prevailing price in the market. Hence only one price prevails in the market.
5. Perfect mobility of factors : In perfect competition the factors of production are perfectly mobile. Factors can easily be mobile from one industry to other industry (or one firm to another firm) without any difficulty.
6. No transportation cost : Transportation cost remains zero in perfect competition due to which one price prevails in the market.

Question 28.
How does price determination in monopoly ?
Answer:
A monopolist charges, different prices from different consumers, called price discrimination. A monopolist has complete control over price and can also practice price discrimination.

Full control over price under monopoly does not mean monopolist can sell any amount of the commodity at any price. Once the monopolist fixes price of the commodity quantity demanded will entirely depend upon the buyers.

If the buyers feel that price is high, quantity demanded, will be low and vice-versa. Accordingly, there is an inverse . relationship between priede fixed by the monopolist and quantity sold by the monopoly firm or quantity demanded of the monopoly product. Thus, demand curve facing a monopoly firm is downward sloping.

Question 29.
Explain different types of Economic policy.
Answer:
Economic system : It is a structure of such institutions with which all economic activities are operated in the society. Every economy is based on an economic system which can be divided into 3 categories.

1. Capitalist economy or Market economy
2. Socialist economy or Planned economy
3. Mixed economy.

1. Market economy contains the following important features :

• Private property : Capitalist economic system recognises ‘Law of inheritance’ and right of individual private property. It also ensures to transfer the property of dead person to its heir.
• Economic freedom : Capitalist economy grants various economic freedoms to the individual like freedom to work. Freedom of choice of consumption and saving and investment.
• Competition : Competition is an essential features of market. Demand and supply takes places due to competition appearing in the economy.
• Price mechanism : In this economy prices are determined by the automatic adjustment of price mechanism price in market is determined at the point where demand and supply forces become equal.

2. Socialist Economy : The salient features of this economics my all as follows :

• Social ownership : In this economy social ownership is found on factors of production. These factors are used for the welfare of the society as a whole. Right to individual property has no place in socialist economy rather it is profited to only self-consumption goods.
• Passive role of price mechanism : In this economy prices are not determined by price mechanism, rather government take the use of accounting prices which are determined by govt, itself on the basis of social interest.
• Absence of competition : Socialist economy
  works on planning and direction as a result of which competition remains absent in the economy.

3. Mixed Economy : It contains the following economic features:

• Co-existence of private and public ownership : Private and public sectors co-exist in the mixed economy. Both private ownership and profit motive are found in such economic system. Law of inheritance finds a place in the economy but government imposes progressive taxation to attain economic equality.
• Economic freedom : Though enough state interference is found in mixed economy people enjoy limited economics freedom of choice, production investment and saving. Govt, adopts many controls so check the unlimited economic freedom of the individual.
• Price system : Both price mechanism and profit motive determine the price system simultaneously in the
  mixed economy. Profit motive is managed by the govt. So that it may not hit the motive of social welfare.

Question 30.
Explain different process of measurement of national income.
Answer:
Measurement of national income : Three steps of value addition are as follows :
(i) First Step : Identification and classfication of productive enterprise at the very first step, we are to identify and classify various productive enterprises of an economy. Broadly, we can classify the economy into following three sectors:

• Primary sector: It is that sector which produces goods by exploiting natural resources like land, water, forests, mines etc.
• Secondary sector : This sector is also as manufacturing sector. It transforms one type of commodity into another, using men, machines and materials.
• Teritory sector : This sector is also known as service sector, which provides useful services to primary and secondary sector.

(ii) Second Step: Calculation of net value of output To estimate the net value added in each identified
enterprise in step first, the following estimates are calculated:

• Value of output,
• Value of intermediate consumption,
• Consumption of fixed capital i.e. depreciation. Value added + Value of Output – Intermediate consumption- Net Indirect taxes Hence, Net value Value added by Added = Primary sector + value added by secondary sector + value added by teritory sector.

(iii) Third step : Calculation of net factor income – road. The third and final step in the estimation of national income is to estimate the net factor income earned from abroad and add it to the net domestic product at factor.
This gives us the national income.
NNP_FC = NDP_FC + NFIA
Net National Product  Net Domestic product at factor cost = of factor cost
Or, National income + Net factor income from

Question 31.
Define different method of exchange rate?
Answer:
Exchange rate is mainly Of two types are as follows:

1. Fixed exchange rate
2. Flexible exchange rate

1. Fixed rate of exchange refers to that rate of exchange which is fixed by the government. It generally does not change or the changes can take place within a fixed limit only. In gold standard, exchange rate was fixed because changes in exchange rate could take place within certain limits and these limits were called ‘gold points’. Historically the two forms of fixed exchange rate were :

• Gold standard system of exchange rate
• Bretton woods system of exchange rate

2. Flexible exchange rate is that rate which is determined by market forces. Change in flexible exchange rate occur on account of change in market demand and supply. Flexible exchange rate is also called floating exchange rate. Thus, flexible rate is free to fluctuate according to the changes, in the demand and supply of foreign currency.
Hence, R = ∫(D, S)
i .e. Exchange rate is a function of demand and supply.

Question 32.
How many types of credit controlling in central bank ?
Answer:
The two types of credit controlling in central bank are as follows :

1. Quantitative methods
2. Qualitative or Selective methods.

1. Quantitative Method: It refers to those methods of credit control which are used by the central bank to influence the total volume of credit without regard for the purpose for which the credit is put. Quantitaitve credit control methods are :

• Bank rate : The bank rate is the rate of which the central bank is prepared to discount the first class bills of exchanges and grant loans of to commercial banks. This is the indirect important method for controlling credit money.
• Open market operations : Open market operations means “purchase or sale of government and other approved securities by the central bank in money and capital market.”
• Change in cash reserve ratio : When the cash flow or credit is to be increased, cash reserve ratio is reduced and when the cash flow or credit is to be reduced, cash reserve ratio is increased.
• Change in statutory liquidity ratio: Every bank is required to maintain a fix percentage of its assets in the form of cash or other liquid assets, called SLR.

2. Qualitative or Selective method : Qualitative or selective methods are those methods which are used by the central bank to regulate the flow of credit into particular directions of the economy.
The important qualitative methods of credit control are :

• Rationing of credit: Central bank is the lender of last resort. So, it can adopt the measures of credit rationing for credit control.
• Regulation of consumer’s credit : In this method the credit given to durable consumer goods is controlled. In days of inflation, consumer’s credit is squeezed and in days of deflation, credit is expanded.
• Change in margin requirements : Marginal requirement is the difference between the current value of physical security offered for loans and the value of loans granted. Central bank determines marginal requirement ratio for different commodities.
• Direct Action : Central bank can take direct action against any commercial bank if the latter do not follow central banks direction.

Question 33.
Why the slope of demand curve is downward ?
Answer:
Downward slope of demand curve indicated that more is purchased in response to fall in price. It is positive when increase in income causes increase in demand. It occurs in case of normal goods. Income effect is negative when increase in income causes decreases in demand. It occurs in case of inferior, goods, thus, there is inverse relationship between price of a commodity and its quantity demanded. This may be explained in terms of the following factors :

1. Law of diminishing marginal utility: According to this law as a consumer in a given time, increases the consumption of a commodity, the utility from each successive unit goes on diminishing. It is therefore, clear that with fall in price, more units, of a commodity will be demanded and with rise in price, less units, of a commodity will be demanded.
2. Income effect : Income effect is the effect on the change in the quality demanded when the real income of buyer changes as a result of the change in the price of commodity alone.
3. Substitution effect : Substitution effect refers to substitution of one commodity for the other when it becomes relatively cheaper.
4. Size of consumer group :’When the price of a commodity fall many consumer who were not buying it at its previous price begin to purchase it.
5. Different uses : Many goods have alternative uses grams are used for human consumption as well as for the consumption of horses

Bihar Board 12th Physics Objective Questions and Answers

Bihar Board 12th Physics Objective Answers Chapter 3 Current Electricity

Question 1.
1 ampere current is equivalent to
(a) 6.25 × 10¹⁸ electrons s^-1
(b) 2.25 × 10¹⁸ electrons s^-1
(c) 6.25 × 10¹⁴ electrons s^-1
(d) 2.25 × 10¹⁴ electrons s^-1
Answer:
(a) 6.25 × 10¹⁸ electrons s^-1

Question 2.
In an atom electrons revolves around the nucleus along a path of radius 0.72 Å making 9.4 x 10¹⁸ revolution per second. The equivalent current is
(e = 1.6 × 10^-19 C)
(a) 1.2 A
(b) 1.5 A
(c) 1.4 A
(d) 1.8 A
Answer:
(b) 1.5 A

Question 3.
The direction of the flow of current through electric circuit is
(a) from low potential to high potential.
(b) from high potential to low potential.
(c) does not depend upon potential value.
(d) current cannot flow through circuit.
Answer:
(b) from high potential to low potential.

Question 4.
The electrical resistance of a conductor depends upon
(a) size of conductor
(b) temperature of conductor
(c) geometry of conductor
(d) all of these
Answer:
(d) all of these

Question 5.
A wire of resistance 4Ω is used to wind a coil of radius 7 cm. The wire has a diameter of 1.4 mm and the specific resistance of its material is 2 × 10^-7 Ω m. The number of turns in the coil is
(a) 50
(b) 40
(c) 60
(d) 70
Answer:
(d) 70
Solution:
(d) Let n be the number of turns in the coil.
Then total length of wire used,

Question 6.
Space between two concentric spheres of radii r₁ and r₂, such that r₁ < r₂, is filled with a material of resistivity ρ . Find the resistance between inner and outer surface of the material.

Answer:
(b) \(\frac{r_{2}-r_{1}}{r_{1} r_{2}} \frac{\rho}{4 \pi}\)
Solution:

Question 7.
The I-V characteristic shown in figure represents
(a) ohmic conductors
(b) non-ohmic conductors
(c) insulators
(d) superconductors
Answer:
(b) non-ohmic conductors

Question 8.
Range of resistivity for metals is
(a) 10^-6 Ω m to 10^-4 Ω m
(b) 10^-7 Ω m to 10^-5 Ω m
(c) 10^-8 Ω m to 10^-6 Ω m
(d) 10^-9 Ω m to 10^-7 Ω m
Answer:
(c) 10^-8 Ω m to 10^-6 Ω m

Question 9.
Wire bound resistors are made by
(a) winding the wires of an alloy viz, Cu, Al, Ag
(b) winding the wires of an alloy viz, Si, Tu, Fe
(c) winding the wires of an alloy viz, Ge, Au, Gr
(d) winding the wires of an alloy viz, manganin, constantan, nichrome.
Answer:
(d) winding the wires of an alloy viz, manganin, constantan, nichrome.

Question 10.
The resistivity of alloy manganin is
(a) Nearly independent of temperature
(b) Increases rapidly with increase in temperature
(c) Decreases with increase in temperature
(d) Increases rapidly with decrease in temperature
Answer:
(a) Nearly independent of temperature

Question 11.
What is the order of magnitude of the resistance of a dry human body ?
(a) 10 Ω
(b) 10 KΩ
(c) 10 MΩ
(d) 10 μΩ
Answer:
(b) 10 KΩ

Question 12.
Two copper wires of length l and 21 have radii, r and 2r respectively. What is the ratio of their specific resistances ?
(a) 1 : 2
(b) 2 : 1
(c) 1 : 1
(d) 1 : 3
Answer:
(c) 1:1

Question 13.
Nichrome or Manganin is widely used in wire bound standard resistors because of their
(a) temperature independent resistivity
(b) very weak temperature dependent resistivity
(c) strong dependence of resistivity with temperature
(d) mechanical strength
Answer:
(b) very weak temperature dependent resistivity

Question 14.
An electric heater is connected to the voltage supply. After few seconds, current get its steady value then its initial current will be
(a) equal to its steady current
(b) slightly higher than its steady current
(c) slightly less than its steady current
(d) zero
Answer:
(b) slightly higher than its steady current

Question 15.
In the circuit shown in figure heat developed across 2 Ω,4 Ω and 3 Ωresistances are in the ratio of

(a) 2 : 4 : 3
(b) 8 : 4 : 12
(c) 4 : 8 : 27
(d) 8 : 4 : 27
Answer:
(d) 8 : 4 : 27

Question 16.
The total resistance in the parallel combination of three resistances 9 Ω,7 Ω, and 5Ω is
(a) 1.22 Ω
(b) 2.29 Ω
(c) 4.22 Ω
(d) 2.02 Ω
Answer:
(d) 2.02 Ω
Solution:
(d) In the parallel combination of three resistances, the equivalent resistance is

Question 17.
Five equal resistances of 10 £2 are connected between A and B as shown in figure. The resultant resistance

(a) 10Ω
(b) 5Ω
(c) 15Ω
(d) 6Ω
Answre:
(b) 5Ω
Solution:
(b) According to the given circuit 10 Ω and 10 Ω resistances are connected in series.
∴ R’= 10 + 10 = 20Ω
Again 10 Ω and 10Ω resistances are connected in series
∴R”= 10 + 10 = 20 Ω
R’, R” and 10 Ω all connected in parallel than

Question 18.
A copper cylindrical tube has inner radius a and outer radius b. The resistivity is P. The resistance of the cylinder between the two ends is

Answer:
(c) \(\frac{\rho^{f}}{\pi\left(b^{2}-a^{2}\right)}\)

Question 19.
A and B are two points on a uniform ring of resistance 15Ω . The ∠AOB = 45°. The equivalent resistance between A and B is

(a) 1.64 Ω
(b) 2.84 Ω
(c) 4.57 Ω
(d) 2.64 Ω
Answer:
(a) 1.64 Ω

Question 20.
The reading of ammeter shown in figure is

(a) 6.56 A
(b) 3.28 A
(c) 2.18 A
(d) 1.09 A
Answer:
(d) 1.09 A

Question 21.
In a circuit a cell with internal resistance r is connected to an external resistance R. The condition for the maximum current that drawn from the cell is
(a) R = r
(b) R < r
(c) R > r
(d) R = 0
Answer:
(d) R = 0

Question 22.
In parallel combination of n cells, we obtain
(a) more voltage
(b) more current
(c) less voltage
(d) less current
Answer:
(b) more current

Question 23.
If n cells each of emf e and internal resistance r are connected in parallel, then the total emf and internal resistances will be

Answer:
(a) \(\varepsilon, \frac{\mathrm{r}}{\mathrm{n}}\)

Question 24.
The potential difference between A and B as shown in figure is

(a) 1 V
(b) 2 V
(c) 3 V
(d) 4 V
Answer:
(a) 1 V
Solution:
(a) Resistance of the upper arm CAD = 2 Ω +3 Ω = 5 Ω
Resistance of the lower arm CBD = 3 Ω +2 Ω =5 Ω

As the resistance of both arms are equal, therefore same amount of current flows in both the arms. Current through each arm CAD or CBD = 1A

Potential difference across C and A is
V_C – V_B = (2Ω) (1 A)
= 2 V …..(i)
Potential difference across C and B is
V_C – V_B = (3Ω) (1 A)
= 3 V ………..(ii)
Subtracting (i) from (ii), we get V_A – V_B = 3V – 2V = 1V

Question 25.
In a Wheatstone bridge if the battery and galvanometer are interchanged then the deflection in galvanometer will
(a) change in previous direction
(b) not change
(c) change in opposite direction
(d) none of these
Answer:
(b) not change

Question 26.
In a Wheatstone’s network, P = 2Ω, Q = 2Ω, R = 2Ω, and S = 3Ω The resistance with which S is to be shunted in order that the bridge may be balanced is
(a) 1Ω
(b) 2Ω
(c) 4Ω
(d) 6Ω
Answer:
(d) 6Ω
Solution:
(d) Let x be the resistance shunted with S for the bridge to be balanced.
For a balance Wheatone’s bridge

Question 27.
When a metal conductor connected to left gap of a meter bridge is heated, the balancing point
(a) shifts towards right
(b) shifts towards left
(c) remains unchanged
(d) remains at zero
Answer:
(a) shifts towards right

Question 28.
In a meter bridge experiment, the ratio of the left gap resistance to right gap resistance is 2 : 3, the balance point from left is
(a) 60 cm
(b) 50 cm
(c) 40 cm
(d) 20 cm
Answer:
(c) 40 cm
Solution:

Question 29.
Which of the following characteristics of electrons determines the current in a conductor ?
(a) Drift velocity alone
(b) Thermal velocity alone
(c) Both drift velocity and thermal velocity
(d) Neither drift not thermal velocity
Answer:
(a) Drift velocity alone

Bihar Board 12th Chemistry Objective Questions and Answers

Bihar Board 12th Chemistry Objective Answers Chapter 3 Electrochemistry

Question 1.
Which of the following is the correct cell representation for the given cell reaction ?
Zn + H₂SO₄→ ZnSO₄ + H₂
(a) Zn|Zn²⁺||H ⁺ |H₂
(b) Zn|Zn²⁺||H ⁺ ,H₂|Pt
(c) Zn |ZnSO₄| |H₂SO₄| Zn
(d) Zn |H₂SO₄||ZnSO₄| H₂
Answer:
(b) Zn|Zn²⁺||H ⁺ ,H₂|Pt

Question 2.
The cell reaction of the galvanic cell:

(a) Hg + Cu²⁺→ Hg²⁺+Cu
(b) Hg + Cu²⁺→ Cu⁺Hg⁺
(c) Cu + Hg → CuHg
(d) Cu + Hg²⁺→ Cu²⁺ Hg
Answer:
(d) Cu + Hg²⁺→ Cu²⁺ Hg

Question 3.
Which of the following reaction is possible at anode ?
(a) 2Cr³⁺ +7H₂O → Cr₂O₇^2- + 14H⁺
(b) F₂ → 2F^–
(c) (1/2)O₂ +2H⁺ → H₂O
(d) None of these.
Answer:
(a) 2Cr³⁺ +7H₂O → Cr₂O₇^2- + 14H⁺

Question 4.
In the cell, |Zn²⁺| |Cu²⁺|Cu, the negative terminals ………..
(a) Cu
(b) Cu²⁺
(c) Zn
(d) Zn²⁺
Answer:
(c) Zn

Question 5.
In a cell reaction,

If the concentration of Cu²⁺ ions is doubled then Eº_Cell will be
(a) doubled
(b) halved
(c) increased by four times
(d) unchanged
Answer:
(d) unchanged

Question 6.
A standard hydrogen electrode that a zero potential because ……………..
(a) hydrogen can be most’easily oxidised
(b) hydrogen has only one electron
(c) the electrode potential is assumed to be zero
(d) hydrogen is the lightest element.
Answer:
(c) the electrode potential is assumed to be zero

Question 7.
Which of the following is the correct order in which metals displace each other from the salt solution of their salts  ?
(a) Zn, Al, Mg, Fe, Cu
(b) Cu, Fe, Mg, Al, Zn
(c) Mg, Al, Zn, Fe, Cu
(d) Al, Mg, Fe, Cu, Zn
Answer:
(d) Al, Mg, Fe, Cu, Zn

Question 8.
Fluorine is the best oxidising agent because it has ………..
(a) highest electron affinity
(b) highest reduction potential
(c) highest oxidation potential
(d) lowest electron affinity.
Answer:
(b) highest reduction potential

Question 9.
At 25°C, Nemst equation is …………..

Answer:
(a)

Question 10.
The correct Nernst equation for the given cell

Answer:

Question 11.
What will be the emf of the following concentration cell at 25°C ?
Ag_(s)| AgNO₃(0.01M)| | AgNO₃(0.05M)| Ag_(s)
(a) 0.828 V
(b) 0.0413 V
(c) -0.0413 V
(d) -0.828 V
Answer:
(b) 0.0413 V

Question 12.
What will be the reduction potential for the following half-cell reaction at 298 K ? [Given: [Ag⁺] = 0.1 M and
E°_e„ = +0.80 V)] ………….
(a) 0.741V
(b) 0.80 V
(c) -0.80 V
(d) -0.741V
Answer:
(a) 0.741V

Question 13.
For the cell reaction: 2Cu_(aq) → Cu_(s) + Cu²⁺ the standard ceil potential is 0.36 V. The equilibrium constant for the reaction is ………….
(a) 1.2 x 10⁶
(b) 7.4 x 10¹²
(c) 2.4 x 10⁶
(d) 5.5 x 10⁸
Answer:
(a) 1.2 x 10⁶

Question 14.
E°_cell for the reaction, 2H₂O^–+ H₃O⁺ + OH” at 25°C is -0.8277 V. The equilibrium constant for the reaction is ………….
(a) 10^-14
(b) 10^-23
(c) 10^-7
(d) 10^-21
Answer:
(a) 10^-14

Question 15.
Cell reaction is spontaneous, when …………….
(a) E°_d is negative
(b) ΔG° is negative
(c) E°_oxid is positive
(d) ΔG° is positive
Answer:
(b) ΔG° is negative

Question 16.
ΔG° f°^r the reaction, Cu²⁺+ Fe → Fe²⁺ + Cu is

(a) 11.44 kJ
(b) 180.8 kJ
(c) 150.5 kJ
(d) 28.5 kJ
Answer:
(c) 150.5 kJ

Question 17.
Units of the properties measured are given below. Which of the properties has not been matched correctly ?
(a) Molar conductance = S m² mol^-1
(b) Cell constant = m^-1
(c) Specific conductance = S m²
(d) Equivalent conductance = S m² (g eq)^-1
Answer:
(c) Specific conductance = S m²

Question 18.
Molar conductivity of 0.15 M solution of KCl at 298 K, if its conductivity is 0.0152 S cm^-1 will be
(a) 124 Ω^-1 cm²    mol^-1
(b) 204  Ω^-1 cm² mol^-1
(c) 101 Ω^-1 cm² mol^-1
(d) 300  Ω^-1 cm² mol^-1
Answer:
(c) 101 Ω^-1 cm²   mol^-1

Question 19.
The molar conductivity is maximum for the solution of concentration
(a) 0.004 M
(b) 0.002 M
(c) 0.005 M
(d) 0.001 M
Answer:
(d) 0.001 M

Question 20.
Specific conductance of 0.1 M NaCl solution is 1.01 x 10^-2 ohm^-1 cm^-1. Its molar conductance in ohm^-1 cm² mol^-1
(a) 1.01 x 10²
(b) 1.01 x 10³
(c) 1.01 x 10⁴
(d) 1.01
Answer:
(a) 1.01 x 10²

Question 21.
When water is added to an aqueous solution of an electrolyte, what is the change in specific conductivity of the electrolyte ?
(a) Conductivity decreases
(b) Conductivity increases
(c) Conductivity remain same
(d) Conductivity does not depend on number of ions
Answer:
(a) Conductivity decreases

Question 22.
Mark the correct choice of electrolytes represented in the graph.

(a) A → 4 NH₄OH, B → NaCl
(b) A →NH₄OH,B → NH₄Cl
(c) A → CH₃COOH, B → 4CH₃COONa
(d) A → KCl, B → 4 NH₄OH
Answer:
(d) A → KCl, B → 4 NH₄OH

Question 23.
Molar conductivity of NH₄OH can be calculated by the equation,

Answer:
(c)

Question 24.
Limiting molar conductivity of NaBr is
(a) Δ°_mNaBr = Δ°_mNaCl + Δ°_mKBr
(b) Δ°_mNaBr = Δ°_mNaCl + Δ°_mKBr – Δ°_mKCl
(c) Δ°_mNaBr = Δ°_mNaOH + Δ°_mNaBr – Δ°_mNaCl
(d) Δ°_mNaBr = Δ°_mNaCl – Δ°_mNaBr
Answer:
(b) Δ°_mNaBr = Δ°_mNaCl + Δ°_mKBr – Δ°_mKCl

Question 25.
Δ°_m(NH₄OH) is equal to …………..
(a) Δ°_{m (NH4OH)} + Δ°_{m (NH4a) –}  -Δ°_m(HCl)
(b) Δ°_m(NH4Cl) + Δ°_{m (NaOH) –} Δ°_m(Nao)
(c) Δ°_m(NH₄Cl) + Δ°_m(NaCl) –  Δ°_m(NaOH)
(d) Δ°_m(NaOH) +Δ°_m(NaCI) – Δ°_m(NH₄Cl)
Answer:
(b) Δ°_m(NH4Cl) + Δ°_{m (NaOH) –} Δ°_m(Naa)

Question 26.
In an electrolytic cell, the flow of electrons is
(a) from cathode to anode in the solution
(b) from cathode to anode through external supply
(c) from cathode to anode through internal supply
(d) from anode to cathode through internal supply.
Answer:
(c) from cathode to anode through internal supply

Question 27.
How long would it take to deposit 50 g of Ai from an electrolytic cell containing Al₂O₃ using a current of 105 ampere
(a) 54 h
(b) 1.42 h
(c) 32 h
(d) 2.15 h
Answer:
(b) 1.42 h

Question 28.
The charge required for reducing 1 mole of MnO₄ to Mn²⁺ is ……………….
(a) 93 x 10⁵ C
(b) 2.895 x  10⁵ C
(c) 4.28 x  10⁵ C
(d) 4.825 x  10⁵ C
Answer:
(d) 4.825 x  10⁵ C

Question 29.
How much electricity in terms of Faraday is required to  produce 100 g of Ca from molten CaCl₂ ?
(a) IF
(b) 2F
(c) 3 F
(d) 5F
Answer:
(a) IF

Question 30.
How many coulombs of electricity is required to reduce 1 mole of Cr₂O² in acidic medium ?
(a) 4 x  96500C
(b) 6 x  96500 C
(c) 2 x 96500 C
(d) 1 x  96500 C
Answer:
(b) 6 x  96500 C

Question 31.
How much metal will be deposited when a current of 12 ampere with 75% efficiency is passed through the cell for 3 h ? (Given : Z = 4 x 10^-4)
(a) 32.4 g
(b) 38.8 g
(c) 0 g
(d) 22.4 g
Answer:
(b) 38.8 g

Question 32.
How many moles of Pt may be deposited on the cathode when 0.80 F of electricity is passed through a 1.0 M solution of Pt⁴⁺ ?
(a) 0.1 mol
(b) 0.2  mol
(c) 4 mol
(d) 0.6  mol
Answer:
(b) 0.2  mol
(b) Pt⁴⁺ + 4e^– → Pt
4 moles of electricity or 4 F of electricity is required to deposit 1 mole of Pt.
0. 80 F of electricity will deposit
\(\frac{1}{4}\) 0.80 = 0.20 mol

Question 33.
If 54 g of silver is deposited during an electrolysis reaction, how much aluminium will be deposited by the same amount of electric current ?
(a) 2.7 g
(b) 4.5  g
(c) 27 g
(d) 5.4  g
Answer:
(b) 4.5g

Question 34.
During the electrolysis of dilute sulphuric acid, the following process is possible at anode.

Answer:
(a)

Question 35.
When a lead storage battery is discharged,
(a) lead sulphate is consumed
(b) oxygen gas is evolved
(c) lead sulphate is formed
(d) lead sulphide is formed.
Answer:
(c) lead sulphate is formed

Question 36.
The reaction which is taking place in nickel-cadmium battery can be represented by which of the following equation
(a) Cd + NiO₂ + 2H₂O → 4 Cd(OH)₂ + Ni(OH)₂
(b) Cd + NiO₂ + 2 OH⁺ → Ni + Cd(OH)₂
(c) Ni + Cd(OH)₂ → Cd + Ni(OH)₂
(d) Ni(OH)₂ +Cd(OH)₂ → Ni + Cd + 2H₂O
Answer:
(a) Cd + NiO₂ + 2H₂O → 4 Cd(OH)₂ + Ni(OH)₂

Question 37.
Which of the following reactions does not take place during rusting ?
(a) 4₂ CO₃ 2H⁺ + CO⁺
(b) 4Fe²⁺ + O_2(dry) → Fe₂O₃
(c) 4Fe²⁺ +O₂ +4H₂O → 2Fe₂O₃ +8H⁺
(d) Fe₂O₃ + xH₂O → Fe₂O₃. x H₂O
Answer:
(a) 4₂ CO₃ 2H⁺ + CO⁺

Question 38.
Which of the following reactions does not take place during rusting ?
(a)

(b) 4Fe²⁺ + O_2(dry) → Fe₂O₃
(c) 4Fe²⁺ + O₂ +4H₂O → 2Fe₂O₃ +8H⁺
(d) Fe₂O₃ + xH₂O → Fe₂O₃. xH₂O
Answer:
(b) 4Fe²⁺ + O_2(dry) → Fe₂O₃

Question 39.
The difference between the electrode potentials of two electrodes when no current is drawn through the cell is called
(a) cell potential
(b) cell emf
(c) potential difference
(d) cell voltage
Answer:
(b) cell emf

Question 40.
An electrochemical cell can behave like an electrolytic cell when ___
(a) ^Ecell = 0
(b) E_{cell >} E_ext
(c) E_{extl >} E_cell
(d) E_cell = E_ext
Answer:
(c) E_{extl >} E_cell

Question 41.
Use the data given in Q. 61 and find out the most stable ion in its reduced form.
(a) Cl-
(b) Cr³⁺
(c) Cr
(d) Mn²⁺
Answer:
(d) Mn²⁺

Question 42.
Use the data of Q. 61 and find out the most stable oxidised species…….
(a) Cr³⁺
(b) MnO₄
(c) Cr₂O^2-
(d) Mn²⁺
Answer:
(a) Cr³⁺

Question 43.
The quantity of charge required to obtain one mole of aluminium from Al₂O₃ is____________
(a) 1F
(b) 6F
(c) 3F
(d) 2F
Answer:
(c) 3F

Question 44.
The cell constant of a conductivity cell_____________
(a) changes with change of electrolyte
(b) changes with change of concentration of electrolyte
(c) changes with temperature of electrolyte
(d) remains constant for a cell
Answer:
(d) remains constant for a cell

Question 45.
While charging the lead storage battery___________
(a) PbSO₄ anode is reduced to Pb
(b) PbSO₄ cathode is reduced to Pb
(c) PbSO₄ cathode is oxidised to Pb
(d) PbSO₄ anode is oxidised to PbO₂
Answer:
(a) PbSO₄ anode is reduced to Pb

Bihar Board 12th Physics Objective Questions and Answers

Bihar Board 12th Physics Objective Answers Chapter 15 Communication Systems

Question 1.
Who invented world wide web?
(a) J.C.R. Licklider
(b) Tim Berners-Lee
(c) Alexander Graham Bell
(d) Samuel F.B. Morse
Answer:
(b) Tim Berners-Lee

Question 2.
Essential elements of a communication system are
(a) transmitter and receiver
(b) receiver and communication channel
(c) transmitter and communication channel
(d) transmitter, communication channel and receiver
Answer:
(d) transmitter, communication channel and receiver

Question 3.
Which of the following is an example of point to point communication mode?
(a) Radio
(b) Television
(c) Telephony
(d) All of these
Answer:
(c) Telephony

Question 4.
Which among the following is not a basic terminology used in electronic communication systems?
(a) Transducer
(b) Transmitter
(c) Telegraph
(d) Attenuation
Answer:
(c) Telegraph

Question 5.
Which of the following is not a transducer?
(a) Loudspeaker
(b) Amplifier
(c) Microphone
(d) All of these
Answer:
(b) Amplifier

Question 6.
The loss of strength of a signal while propagating through a medium is known as
(a) reception
(b) absorption
(c) transmission
(d) attenuation
Answer:
(d) attenuation

Question 7.
The process of increasing the strenth of a signal using an electronic circuit is called
(a) amplification
(b) modulation
(c) demodulation
(d) transmission
Answer:
(a) amplification

Question 8.
Modem is a device which performs
(a) modulation
(b) demodulation
(c) rectification
(d) modulation and demodulation
Answer:
(d) modulation and demodulation

Question 9.
Modulation is the process of superposing
(a) low frequency audio signal on high frequency radio waves
(b) low frequency radio signals on low frequency audio . wave
(c) high frequency radio signal on low frequency audio signal
(d) high frequency audio signal on low frequency radio waves
Answer:
(a) low frequency audio signal on high frequency radio waves

Question 10.
The device which is a combination of a receiver and a transmitter is
(a) Amplifier
(b) Repeater
(c) Transducer
(d) Modulator
Answer:
(b) Repeater

Question 11.
Large bandwidth for higher data rate is achieved by using
(a) high frequency carrier wave
(b) high frequency audio wave
(c) low frequency carrier wave
(d) low frequency audio wave
Answer:
(a) high frequency carrier wave

Question 12.
In a video signal for transmission of picture, what value of bandwidth used in communication system?
(a) 2.4 MHz
(b) 4.2 MHz
(c) 24 MHz
(d) 42 MHz
Answer:
(b) 4.2 MHz

Question 13.
Which of the following is an example of broadcast mode of communication?
(a) Radio
(b) Television
(c) Mobile
(d) Both (a) & (b)
Answer:
(d) Both (a) & (b)

Question 14.
Which of the following devices is full duplex?
(a) Mobile phone
(b) Walky-talky
(c) Loud speaker
(d) Radio
Answer:
(a) Mobile phone

Question 15.
FM broadcast is preferred over AM broadcast becuase
(a) it is less noisy
(b) reproduction is of much better quality
(c) it is more noisy
(d) both (a) and (b)
Answer:
(d) both (a) and (b)

Question 16.
The frequency band used in the downlink of satellite communication is
(a) 9.5 to 2.5 GHz
(b) 896 to 901 MHz
(c) 3.7 to 4.2 GHz
(d) 840 to 935 MHz
Answer:
(c) 3.7 to 4.2 GHz

Question 17.
The radio waves of frequency 30 MHz to 300 MHz belong to
(a) high frequency band
(b) very high frequency band
(c) ultra high frequency band
(d) super high frequency band
Answer:
(b) very high frequency band

Question 18.
Ground waves have wavelength
(a) less than that of sky waves
(b) greater than that of sky waves
(c) less than that of space waves
(d) equal to that of space waves
Answer:
(b) greater than that of sky waves

Question 19.
The mode of propagation used by short wave broadcast services is
(a) space wave
(b) sky wave
(c) ground wave
(d) both (a) and (c)
Answer:
(b) sky wave

Question 20.
The skip zone in radio wave transmission is that range where
(a) there is no reception of either ground wave or sky wave
(b) the reception of ground-wave is maximum but that of sky wave is minimum
(c) the reception of ground wave is minimum, but that of sky wave is maximum
(d) the reception of both ground and sky wave is maximum
Answer:
(a) there is no reception of either ground wave or sky wave

Question 21.
The waves that are bent down by the ionosphere are
(a) ground waves
(b) surface waves
(c) space waves
(d) sky waves
Answer:
(d) sky waves

Question 22.
The maximum line-of-sight distance d_M between two antennas having heights h_T and h_R above the earth is

Answer:
(d)

Question 23.
Frequencies in the UHF range normally propagate by means of
(a) ground waves
(b) sky waves
(c) surface waves
(d) space waves
Answer:
(d) space waves

Question 24.
A ground reciver in line-of-sight communication cannot receive direct waves due to
(a) its low frequency
(b) curvature of earth
(c) its high intensity
(d) smaller antenna
Answer:
(b) curvature of earth

Question 25.
Which of the following modes is used for line of sight communication as well as satellite communication?
(a) Ground wave
(b) Sky wave
(c) Space wave
(d) All of these
Answer:
(c) Space wave

Question 26.
Through which mode of propagation, the radio waves can be sent from one place to another
(a) ground wave propagation
(b) sky wave propagation
(c) space wave propagation
(d) all of them
Answer:
(d) all of them

Question 27.
Which of the following frequency will be suitable for beyond the horizon communication using sky waves?
(a) 10 kHz
(b) 10 MHz
(c) 1 GHz
(d) 1000 GHz
Answer:
(b) 10 MHz

Question 28.
What should be the length of the dipole antenna for a carrier wave of frequency 3 x 10⁸ Hz?
(a) 1 m
(b) 0.5 m
(c) 2 m
(d) 2.5 m
Answer:
(b) 0.5 m

Question 29.
A radio can tune to any station in 7.5 MHz to 12 MHz band. The corresponding wavelength band is
(a) 25 m-40m
(b) 10 m-30m
(c) 20-40 m
(d) 25 m – 35 m
Answer:
(a) 25 m-40m

Question 30.
In frequency modulation
(a) the amplitude of modulated wave varies as frequency of carrier wave
(b) the frequency of modulated wave varies as amplitude of modulating wave
(c) the amplitude of modulated wave varies as amplitude of carrier wave
(d) the frequency of modulated wave varies as frequency of modulating wave
Answer:
(d) the frequency of modulated wave varies as frequency of modulating wave

Question 31.
Audio signal cannot be transmitted because
(a) the signal has more noise.
(b) the signal cannot be amplified for distance communication.
(c) the transmitting antenna length is very small to design.
(d) the transmitting antenna length is very large and impracticable.
Answer:
(d) the transmitting antenna length is very large and impracticable.

Question 32.
The modulation in which pulse duration varies in accordance with the modulating signal is called
(a) PAM
(b) PPM
(c) PWM
(d) PCM
Answer:
(c) PWM

Question 33.
A 300 W carrier is modulated to a depth 75%. The total power in the modulated wave is
(a) 200 W
(b) 284 W
(c) 320 W
(d) 384 W
Answer:
(d) 384 W

Question 34.
A signal wave of frequency 12 kHz is modulated with a carrier wave of frequency 2.51 MHz. The upper and lower side band frequencies are respectively
(a) 2512 kHz and 2508 kHz
(b) 2522 kHz and 2488 kHz
(c) 2502 kHz and 2498 kHz
(d) 2522 kHz and 2498 kHz
Answer:
(d) 2522 kHz and 2498 kHz

Question 35.
The maximum amplitude of an amplitude modulated wave is found to be 15 V while its minimum amplitude is found to be 3 V. The modulation index is
\((a) \frac{3}{2}
(b) \frac{2}{3}
(c) \frac{1}{2}
(d) \frac{1}{3}\)
Answer:
\((b) \frac{2}{3}\)

Question 36.
The LC product of a tuned amplifier circuit require to generate a carrrier wave of 1 MHz for amplitude modulation is
(a) 1.5 x 10^-14 s
(b) 1.2 x 10^-12 s
(c) 3.2 x 10^-12 s
(d) 2.5 x 10^-14 s
Answer:
(d) 2.5 x 10^-14 s

Question 37.
The essential condition for demodulation is

Answer:
(b)

Question 38.
Figure shows a communication system. What is the output power when input signal is 1.01 m W?

(a) 90 mW
(b) 101 mW
(c) 112 m W
(d) 120 mW
Answer:
(b) 101 mW

Question 39.
A 100 m long antenna is mounted on a 500 m tall building. The complex can become a transmission tower for waves with X
(a) ~ 400 m
(b)~25m
(c)~150m
(d)~ 2400 m
Answer:
(a) ~ 400 m

Question 40.
A male voice after modulation-transmission sounds like that of a female to the receiver. The problem is due to
(a) poor selection of modulation index (selected 0<w<l)
(b) poor bandwidth selection of amplifiers
(c) poor selection of carrier frequency
(d) loss of energy in transmission
Answer:
(b) poor bandwidth selection of amplifiers

Question 41.
A basic communication system consists of
(A) transmitter
(B) information source
(C) user of information
(D) channel
(E) receiver

Choose the correct sequence in which these are arranged in a basic communication system.
(a) ABCDE
(b) BADEC
(c) BDACE
(d) BEADC
Answer:
(b) BADEC

Question 42.
Identify the mathematical expression for amplitude modulated wave.
\( (a) A_{c} \sin \left[\left\{\omega_{c}+k_{1} v_{m}(t)\right\} t+\phi\right]\)
\( (b) A_{c} \sin \left\{\omega_{c} t+\phi+k_{2} v_{m}(t)\right\}\)
\( (c) \left\{A_{c}+k_{2} v_{m}(t)\right\} \sin \left(\omega_{n} t+\phi\right)\)
\( (d) A_{c} v_{m}(t) \sin \left(\omega_{c} t+\phi\right)\)
Answer:
\((c) \left\{A_{c}+k_{2} v_{m}(t)\right\} \sin \left(\omega_{n} t+\phi\right)\)

Hints And Explanations

Question 29.
(a) Wavelength corresponding to 7.5 MHz frequency
Answer:
\(\lambda_{1}=\frac{c}{v}=\frac{3 \times 10^{8}}{7.5 \times 10^{6}}=40 \mathrm{m}\)
Wavelength corresponding to 12 MHz frequency
\(\lambda_{2}=\frac{3 \times 10^{8}}{12 \times 10^{6}}=25 \mathrm{m}\)

Question 33.
P_c = 300 W, μ, = 75% = 0.75
Answer:

Question35.
(b) Here, A_c + A_m = 15 V …………………. (i)
A_c – A_m = 3V ………………………… (ii)
Answer:
Solving (I) and (ii), we get, A_c =9 V, A_m = 6 V
∴ Modulation index, \(\mu=\frac{A_{m}}{A_{c}}=\frac{6}{9}=\frac{2}{3}\)

Question 36.
(d) Frequency of tuned amplifier is \(v=\frac{1}{2 \pi \sqrt{L C}}\)
Answer:
As per question, u = 1 MHz = 10⁶ Hz

Question 38.

Answer:
Here, transmission path = 5 km
Loss suffered in transmission path
= – 2 dB km^-1 x 5 km = – 10 dB
Total amplifier gain = 10 dB + 20 dB = 30 dB
Overall gain of signal = 30 dB – 10 dB = 20 dB

Question 39.
(a) Length of antenna, ¡ = 100 m,
As l = \(\frac{\lambda}{4}\) or λ = 4l = 4 x 100 = 400m.

Very Important Questions

Question 1.
The electric Held at a point near an infinite thin sheet of charged conductor is :

Answer:
(c)

Question 2.
Two capacitors C₁ = 2μF and C₂ = 4μF are connected in series and a potential difference (p.d.) of 1200 V is applied across it. The Potential difference across 2μF will be :
(a) 400 V
(b) 600 V
(c) 800V
(d) 900V
Answer:
(c) 800V

Question 3.
In the figure, ifnet force on Q is zero then value of \(\frac{Q}{q}\) is:

Answer:
(b)

Question 4.
When a body is charged, its mass
(a) increases
(b) decreases
(c) remains same
(d) may increase or decrease
Answer:
(d) may increase or decrease

Question 5.
The electric potential due to a small electric dipole at a large distance r from the center of the dipole is proportional to :
\((a) r
(b) \frac{1}{r}
(c) \frac{1}{r^{2}}
(d) \frac{1}{r^{3}}\)
Answer:
\((c) \frac{1}{r^{2}}\)

Question 6.
Minimum number of capacitors of 2pF each required to obtain a capacitance of 5fxF will be
(a) 4
(b) 3
(c) 5
(d) 6
Answer:
(a) 4

Question 7.
The specific resistance of conductor increases with :
(a) increase of temperature
(b) increase of cross-sectional area
(c) decrease in length
(d) decrease of cross-sectional area
Answer:
(a) increase of temperature

Question 8.
The Drift velocity (vd) and applied electric field (E) of a conductor are related as :
\((a) \mathrm{V}_{\mathrm{d}} \propto \sqrt{\mathrm{E}}
(b) \mathrm{V}_{\mathrm{d}} \propto \mathrm{E}
(c) \mathrm{V}_{\mathrm{d}} \propto \mathrm{E}^{2}
(d) v_{d}= Constant\)
Answer:
\((b) \mathrm{V}_{\mathrm{d}} \propto \mathrm{E}\)

Question 9.
A charge ‘q’ moves in a region where electric field ‘E’ and magnetic field ‘B’ both exist, then force on it is :

Answer:
(b)

Question 10.
A bar magnet of magnetic moment M is cut into two parts of equal length. The magnetic moment of either part is :
(a) M
(b) M/2
(c) 2M
(d) Zero
Answer:
(b) M/2

Question 11.
The dimensional formula for \(\frac{1}{2} \varepsilon_{0} \mathbf{E}^{2}\) is identical to that of:

Answer:
(a)

Question 12.
A circular coil of radius R carries a current I. The magnetic field at its center is B. At what distance from the center, on the axis of the coil, the magnetic field will be B/8.
(a) \(\sqrt{2} \mathrm{R}\)
(b) 2R
(c) \(\sqrt{3} \mathrm{R}\)
(d) 3R
Answer:
(c) \(\sqrt{3} \mathrm{R}\)

Question 13.
Magnetic dipole moment is a vector quantity directed from:
(a) South to North Pole
(b) North to South Pole
(c) East to West direction
(d) West to East direction
Answer:
(a) South to North Pole

Question 14.
A wire of magnetic dipole moment M and L is bent into shape of a semicircle of radius r. What will be its new dipole moment?
\((a) \mathrm{M}
(b) \frac{M}{2 \pi}
(c) \frac{M}{\pi}
(d) \frac{2 M}{\pi}\)
Answer:
\((d) \frac{2 M}{\pi}\)

Question 15.
In a closed circuit of resistance 10W, the linked flux varies with time according to relation Φ = 6t² – 5t +1. At t = 0.25 second, the current (in Ampere) flowing through the circuit is :
(a) 0.4
(b) 0.2
(c) 2.0
(d) 4.0
Answer:
(b) 0.2

Question 16.
In A.C. circuit, the current and voltage are given by i = 5 cos wt, and V = 200 sin wt respectively. Power loss in the circuit is :
(a) 20 W
(b) 40W
(c) 1000W
(d) zero
Answer:
(d) zero

Question 17.
The energy of an electromagnetic radiation is 13.2 keV.
This radiation is related to which region of spectrum?
(a) Visible
(b) X-rays
(c) Ultra violet
(d) Infrared
Answer:
(b) X-rays

Question 18.
The image formed by objective lens of a compound Microscope is :
(a) Virtual and diminished
(b) Real and diminished
(c) Real and large
(d) Virtual and Large
Answer:
(c) Real and large

Question 19.
A convex lens is dipped in a liquid, whose refractive index is equal to refractive index of material of lens. Then its focal length will:
(a) become zero
(b) become infinite
(c) decrease
(d) increase
Answer:
(b) become infinite

Question 20.
Critical angle for light moving from medium I to medium II is 6. The speed of light in medium I is v. Then speed in medium II is :

Answer:
(b)

Question 21.
A magnifying glass is to be used at the fixed object distance of 1 inch. If it is to produce an erect image 5 items magnified, its focal length should be :
(a) 0.2″
(b) 0.8″
(c) 1.5″
(d) 5″
Answer:
(c) 1.5″

Question 22.
To remove hyper metropia lens used is :
(a) Convex
(b) Concave
(c) Cylindrical
(d) Plano-convex
Answer:
(a) Convex

Question 23.
Which of the following phenomena taken place when a monochromatic light is incident on a prism?
(a) Dispersion
(b) Deviation
(c) Interference
(d) All of the above
Answer:
(a) Dispersion

Question 24.
Optical fiber communication is based on which of the following phenomena:
(a) Total Internal reflection
(b) Scattering
(c) Reflection
(d) Interference
Answer:
(a) Total Internal reflection

Question 25.
The value of maximum amplitude produced due to interference of two waves is given by- y₁ = 4 sin wt and y₂ = 3 cos wt
(a) 7
(b) 5
(c) 1
(d) 25
Answer:
(b) 5

Question 26.
The phase difference 0 is related to Path difference Δx by:

Answer:
(c)

Question 27.
The resolving power of human eye (in minute) is :
(a) \(\frac{1}{60}\)
(b) 1
(c) 10
(d) \(\frac{1}{2}\)
Answer:
(a) \(\frac{1}{60}\)

Question 28.
A particle of mass m and charged q is accelerated through a potential V. The De-Broglie wavelength of the particle will be :

Answer:
(c)

Question 29.
The number of Photons of frequency 1014 Hz in radiation of 6.62J will be :
(a) 10¹⁰
(b) 10¹⁵
(c) 10²⁰
(d) 10²⁵
Answer:
(c) 10²⁰

Question 30.
The minimum angular momentum of electron in Hydrogen atom will be :
\((a) \frac{h}{\pi} J s
(b) \frac{h}{2 \pi} J s
(c) \mathrm{h} \pi \mathrm{Js}
(d) 2 \pi h J s\)
Answer:
\((b) \frac{h}{2 \pi} J s\)

Question 31.
The atomic number and mass number for a specimen are Z and A respectively. The number of neutrons in the atom will be :
(a) A
(b) Z
(c) A + Z
(d) A-Z
Answer:
(d) A-Z

Question 32.
The quantities, which remain conserved in a nuclear reaction:
(a) Total Charge
(b) Angular momentum
(c) Linear momentum
(d) All the above
Answer:
(d) All the above

Question 33.
Meaning of “FAX” is :
(a) Full Access Transmission
(b) Facsimile Telegraphy
(c) Factual Auto Access
(d) Feed Auto Exchange
Answer:
(b) Facsimile Telegraphy

Question 34.
A semiconductor is cooled from T₁K to T₂K, then its resistance will:
(a) increase
(b) decrease
(c) remain constant
(d) First decrease then increase
Answer:
(a) increase

Question 35.
If the current constant for a transistor are α & β then :
(a) αβ = l
(b) β > l, α < l
(c) α = β
(d) β < l, α > l
Answer:
(b) β > l, α < l

Bihar Board 12th Physics Objective Questions and Answers

Bihar Board 12th Physics Objective Answers Chapter 2 Electrostatic Potential and Capacitance

Question 1.
Which of the following statement is not true ?
(a) Electrostatic force is a conservative force.
(b) Potential at a point is the work done per unit charge in bringing a charge from infinity to that point.
(c) Electrostatic force is non-conservative.
(d) Potential is the product of charge and work.
Answer:
(b) Potential at a point is the work done per unit charge in bringing a charge from infinity to that point.

Question 2.
I volt is equivalent to

Answer:
\(\frac{\text { joule }}{\text { coulomb }}\)

Question 3.
The potential at a point due to a charge of 5 × 10^-7 C located 10 cm away is
(a) 3.5 × 10⁵ V
(b) 3.5 × 10⁴ V
(c) 4.5 × 10⁴ V
(d) 4.5 × 10⁵ V
Answer:
(c) 4.5 × 10⁴ V
Solution:
(c) Here, q = 5 × 10^-7C,r = 10cm = 0.1 m

Potential,

Question 4.
A charge +q is placed at the origin O of x-y axes as shown in the figure. The work done in taking a charge Q from A to B along the straight line AB is

Answer:
(a) \(\frac{\mathrm{qQ}}{4 \pi \varepsilon_{0}}\left(\frac{\mathrm{a}-\mathrm{b}}{\mathrm{ab}}\right)\)

Question 5.
The electric field and the potential of an electric dipole vary with distance r as

Answer:
(d) \(\frac{1}{r^{3}} \text { and } \frac{1}{r^{2}}\)

Question 6.
An electric dipole is placed at the centre of a hollow conducting sphere. Where of the following is correct ?
(a) Electric field is zero at every point of the sphere
(b) Electric field is not zero anywhere on the sphere
(c) The flux of electric field is not zero through the sphere
(d) All of these
Answer:
(b) Electric field is not zero anywhere on the sphere

Question 7.
The distance between H⁺ and Cl^– ions in HCl molecules is 1.38 Å. The potential due to this dipole at a distance of 10 Å on the axis of dipole is
(a) 2.1 V
(b) 1.8 V
(c) 0.2 V
(d) 1.2 V
Answer:
(c) 0.2 V

Question 8.
A cube of side x has a charge q at each of its vertices. The potential due to this charge array at the centre of the cube is

Answer:
(b) \(\frac{4 q}{\sqrt{3} \pi \varepsilon_{0} x}\)

Question 9.
A hexagon of side 8 cm has a charge 4 µC at each of its vertices. The potential at the centre of the hexagon is
(a) 2.7 × 10⁶ V
(b) 7.2 × 10¹¹ V
(c) 2.5 × 10¹² V
(d) 3.4 × 10⁴ V
Answer:
(a) 2.7 × 10⁶ V
Solution:
As shown in the figure, O is the centre of hexagon ABCDEF of each side 8 cm. As it is a regular hexagon OAB, OBC, etc are equilateral triangles,

∴OA = OB = OC = OD = OE = OF = 8 cm = 8 × 10^-2 m The potential at O is

Question 10.
Equipotential surfaces
(a) are closer in regions of large electric fields compared to regions of lower electric fields
(b) will be more crowded near sharp edges of a conductor
(c) will always be equally spaced
(d) both (a) and (b) are correct
Answer:
(d) both (a) and (b) are correct

Question 11.
What is the angle between electric field and equipotential surface ?
(a) 90° always
(b) 0° always
(c) 0°to90°
(d) 0° to 180°
Answer:
(a) 90° always

Question 12.
The work done to move a unit charge along an equipotential surface from P to Q
(a) must be defined as \(-\int_{\mathrm{P}}^{Q} \overrightarrow{\mathrm{E}} \cdot \overrightarrow{\mathrm{d} \ell}\)
(b) is zero
(c) can have a non-zero value
(d) both (a) and (b) are correct
Answer:
(d) both (a) and (b) are correct

Question 13.
The work done in carrying a charge q once round a circle of radius a with a charge Q at its centre is

Answer:
(d) zero

Question 14.
A test charge is moved from lower potential point to a higher potential point. The potential energy of test charge will
(a) remains the same
(b) increase
(c) decrease
(d) becomes zero
Answer:
(c) decrease

Question 15.
Which among the following is an example of polar molecule ?
(a) O₂
(b) H₂
(c) N₂
(d) HCl
Answer:
(d) HCl

Question 16.
Dielectric constant for a metal is
(a) zero
(b) infinite
(c) 1
(d) 10
Answer:
(b) infinite

Question 17.
Metallic sphere of radius R is charged to potential V. Then charge q is proportional to
(a) V
(b) R
(c) both V and R
(d) none of these
Answer:
(c) both V and R

Question 18.
In a parallel plate capacitor, the capacity increases if
(a) area of the plate is decreased
(b) distance between the plates increases
(c) area of the plate is increased
(d) dielectric constant decreases.
Answer:
(c) area of the plate is increased

Question 19.
A parallel plate capacitor having area A and separated by distance d is filled by copper plate of thickness b. The new capacity is

Answer:
(c) \(\frac{\varepsilon_{0} A}{d-b}\)

Question 20.
Figure shows the Held lines of a positive point charge. The work done by the field in moving a small positive charge from Q to P is

(a) zero
(b) positive
(c) negative
(d) data insufficient
Answer:
(c) negative

Question 21.
The charge on 3 μF capacitor shown in the figure is

Answer:
(a) 2 μC
(b) 10 μC
(c) 6 μC
(d) 8 μC
Answer:
(b) 10 μC

Question 22.
Minimum number of capacitors each of 8 μF and 250 V used to make a composite capacitor of 16 μF and 1000 V are
(a) 8
(b) 32
(c) 16
(d) 24
Answer:
(b) 32
Solution:
(b) Minimum number of capacitors in each row

= \(\frac{1000}{250}=4\)
Therefore, 4 capacitors connected in series.
If there are m such rows, then total capacity = m x 2 = 16
∴ m = 16/2 = 8
∴ minimum number of capacitors = 4 x 8 = 32

Question 23.
A parallel plate capacitor is made by placing n equally spaced plates connected alternatively. If the capacitance between any two adjacent plates is C then the resultant capacitance is
(a) nC
(b) C/n
(c) (n + 1)C
(d) (n – 1)C
Answer:
(d) (n – 1)C

Question 24.
A parallel plate air capacitor has a capacitance C. When it is half filled with a dielectric of dielectric constant 5, the percentage increase in the capacitance will be
(a) 400%
(b) 66.6%
(c) 33.3%
(d) 200%
Answer:
(b) 66.6%

Question 25.
A capacitor of capacitance 700 pF is charged by 100 V battery. The electrostatic energy stored by the capacitor is
(a) 2.5 × 10^-8 J
(b) 3.5 × 10^-6 J
(c) 2.5 × 10^-4J
(d) 3.5 × 10^-4J
Answer:
(b) 3.5 × 10^-6 J
Solution:
(b) Here, C = 700 pF = 700 × 10^-12 F, V = 100 V

Energy stored

Question 26.
A 16 pF capacitor is connected to 70 V supply. The amount of electric energy stored in the capacitor is
(a) 4.5 × 10^-12 J
(b) 5.1 × 10^-8 J
(c) 2.5 × 10^-12 J
(d) 3.2 × 10^-8 J
Answer:
(b) 5.1 × 10^-8 J

Question 27.
A metallic sphere of radius 18 cm has been given a charge of 5 × 10^-6 C. The energy of the charged conductor is
(a) 0.2 J
(b) 0.6 J
(c) 1.2 J
(d) 2.4 J
Answer:
(b) 0.6 J
Solution:

Question 28.
Energy stored in a capacitor and dissipated during charging a capacitor bear a ratio
(a) 1 : 1
(b) 1 : 2
(c) 2 : 1
(d) 1 : 3
Answer:
(c) 2 : 1
Solution:
(c) Half of the energy is dissipated during charging a capacitor.

Question 29.
Van deGraaff generator is used to
(a) store electrical energy
(b) build up high voltages of few million volts
(c) decelerate charged particle like electrons
(d) both (a) and (b) are correct
Answer:
(b) build up high voltages of few million volts

Question 30.
Who established the fact of animal electricity ?
(a) Van deGraaff
(b) Count Alessandro Volta
(c) Gustav Robert Kirchhoff
(d) Hans Christian Oersted
Answer:
(b) Count Alessandro Volta

Question 31.
In case of a Van de Graaff generator, the breakdown field of air is
(a) 2 × 108 V m^-1
(b) 3 × 106 V m^-1
(c) 2 × 1CT8 V m^-1
(d) 3 × 104 V m^-1
Answer:
(b) 3 × 106 V m^-1

Question 32.
A capacitor of 4 μF is connected as shown in the circuit. The internal resistance of the battery is 0.5 Ω . The amount of charge on the capacitor plates will be

(a) 0
(b) 4 μC
(c) 16 μC
(d) 8 μC
Answer:
(d) 8 μC

Question 33.
Equipotentials at a great distance from a collection of charges whose total sum is not zero are approximately
(a) spheres
(b) planes
(c) paraboloids
(d) ellipsoids
Answer:
(a) spheres