Category: Class 12

Bihar Board 12th Intermediate Entrepreneurship Model Question Papers, Sample Papers 2019, 2020, 2021 with Answers Pdf free download in Hindi Medium and English Medium.

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Bihar Board 12th Model Papers

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Bihar Board 12th Intermediate Business Studies Model Question Papers, Sample Papers 2019, 2020, 2021 with Answers Pdf free download in Hindi Medium and English Medium.

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Bihar Board 12th Model Papers

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Bihar Board 12th Intermediate Economics Model Question Papers, Sample Papers 2019, 2020, 2021 with Answers Pdf free download in Hindi Medium and English Medium.

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Bihar Board 12th Model Papers

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Bihar Board 12th Intermediate Accountancy Model Question Papers, Sample Papers 2019, 2020, 2021 with Answers Pdf free download in Hindi Medium and English Medium.

Bihar Board 12th Intermediate Accountancy Model Question Papers 2020-2021 Pdf with Answers

Bihar Board 12th Model Papers

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Bihar Board 12th Accountancy Model Question Papers in Hindi Medium

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Bihar Board 12th Chemistry Model Papers

Bihar Board 12th Chemistry Model Question Paper 4 in English Medium

Time : 3 Hours 15 Min
Full Marks: 70

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, candidate should adhere to the words limit as far as practicable.
4. 15 Minutes of extra time has been allotted for the candidates 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.

Objective Type Questions

In the following questions no. from 1 to 35, there is only one correct answer against each question. For each question, mark (darken) the correct answer on the OMR Sheet provided to you. (1 x 35 = 35)

Question 1.
Which type of crystals contains more than one Bravais lattice ?
(a) Hexagonal
(b) Triclinic
(c) Rhombohedral
(d) Monoclinic
Answer:
(d) Monoclinic

Question 2.
For the structure given below the site marked as S is a …………….

(a) tetrahedral void
(b) cubic void
(c) octahedral void
(d) none of these
Answer:
(c) octahedral void

Question 3.
If the radius of an octahedral void is r and radius of atoms in close packing is R, the relation between r and R is
(a) r = 0.414 R
(b) R = 0.414 r
(c) r = 2R
(d) r = \(\sqrt{2} R\)
Answer:
(a) r = 0.414 R

Question 4.
A metal crystallises into a lattice containing a sequence of layers as AB AB AB………………… What percentage of voids are left in the lattice ?
(a) 72%
(b) 48%
(c) 26%
(d) 32%
Answer:
(c) 26%

Question 5.
In ccp arrangement the pattern of successive layers can be designated as
(a) AB AB AB
(b) ABC ABC ABC
(c) AB ABC AB
(d) ABA ABA ABA
Answer:
(b) ABC ABC ABC

Question 6.
A solution is obtained by mixing 200 g of 30% and 300 g of 20% solution by weight. What is the percentage of solute in the final solution ?
(a) 50%
(b) 28%
(c) 64%
(d) 24%
Answer:
(d) 24%

Question 7.
When 1.04 g of BaCl₂ is present in 10⁵ g of solution the concentration of solution is ………….
(a) 104 ppm
(b) 10.4 ppm
(c) 0104 ppm
(d) 104 ppm
Answer:
(b) 10.4 ppm

Question 8.
In the cell, |Zn²⁺| |Cu²⁺|Cu, the negative terminals
(a) Cu
(b)Cu²⁺
(c) Zn
(d) Zn²⁺
Answer:
(d) Zn²⁺

Question 9.
What will be standard cell potential of galvanic cell with the following reaction ?

(a) 74 V
(b) 1.14 V
(c) 34 V
(d) – 0.34 V
Answer:
(c) 34 V                         .

Question 10.
In a reaction 2HI → H₂ + I₂ the concentration of HI decreases from 0.5 mol L^-1 in 10 minutes. What is the rate of reaction during this interval ?
(a) 5 x 10^-3 M min^-1
(b) 5 x 10^-3 M min^-1
(c) 5 x 10^-2 M min^-1
(d) 5 x 10^-2 M min^-1
Answer:
(a) 5 x 10^-3 M min^-1

Question 11.
The rate of disappearance of SO, in the reaction, 2SO₂ + O₂  → 2SO₃ is 1.28 x 10^-5 Ms . 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) 56 x 10^-5 Ms¹
(d) 1.28 x 10^-5  M s^-1
Answer:
(d) 1.28 x 10^-5  M s^-1

Question 12.
Which of the following is a property of physisorption ?
(a) High specificity
(b) Irreversibility
(c) Non-specificity
(d) None of these
Answer:
(c) Non-specificity

Question 13.
Which of the following statement is not correct about physisorption ?
(a) It is a reversible process
(b) It requires less heat of adsorption
(c) It requires activation energy
(d) It takes place at low temperature
Answer:
(c) It requires activation energy

Question 14.
The name of the metal which is extracted from the ore is given below. Mark the example which is not correct.
(a) Malachite – Cu
(b) Calamine – Zn
(c) Chromite – Cr
(d) Dolomite – Al
Answer:
(d) Dolomite – Al

Question 15.
Which of the followings is magnetite ?
(a) Fe₂CO₃
(b) Fe₂O₃
(c) Fe₃O₄
(d) Fe₂O₃.3H₂O
Answer:
(c) Fe₃O₄

Question 16.
Nitrogen can form only one chloride with chlorine which is NCl₃ whereas P can form PCl₃ and PCl₅. This is ……………
(a) due to absence of d-orbitals in nitrogen
(b) due to difference in size of N and P
(c) due to higher reactivity of P towards Cl than N
(d) due to presence of multiple bonding in nitrogen
Answer:
(a) due to absence of d-orbitals in nitrogen

Question 17.
On heating a mixture of NH₄Cl and KNO₂, we get
(a) NH₄NO₃
(b) KNH₄(NO₃)₂
(c) N₂
(d) NO
Answer:
(c) N₂

Question 18.
The melting point of copper is higher than that of zinc because
(a) the s, p as well as d-electrons of copper are involved in metallic bonding
(b) the atomic volume of copper is higher
(c) the d-electrons of copper are involved in metallic bonding
(d) the s as well as d-electrons of copper are involved in metallic bonding
Answer:
(c) the d-electrons of copper are involved in metallic bonding

Question 19.
Zr and Hf have almost equal atomic and ionic radii because of ………………….
(a) diagonal relationship
(b) lanthanoid contraction
(c) actinoid contraction
(d) belonging to the same group
Answer:
(b) lanthanoid contraction

Question 20.
Which of the following primary and secondary valencies are not correctly marked against the compounds ?
(a) [Cr(NH₃)₆]Cl₃, p = 3,s = 6
(b) K₂[Pt(CI₄],p = 2,s = 4
(c) [Pt(NH₃)₂Cl₂],p = 2,s = 4
(d) [Cu(NH₃)₄]SO₄,p = 4,s = 4
Answer:
(d) [Cu(NH₃)₄]SO₄,p = 4,s = 4

Question 21.
When aqueous solution of potassium fluoride is added to the blue coloured aqueous CuSO₄ solution, a green precipitate is formed. This observation can be explained as follows.
(a) On adding KF, H₂O being weak field ligand is replaced by F^– ions forming [CuF₄ ]^2- which is green in colour
(b) Potassium is coordinated to [Cu(H₂O)₄]²⁺ ion present in CuSO₄ and gives green colour
(c) On adding KF, Cu²⁺ are replaced by K⁺ forming a green complex
(d) Blue colour of CuSO₄ and yellow colour of KI form green colour on mixingAnswer:
(a) On adding KF, H₂O being weak field ligand is replaced by F^– ions forming [CuF₄ ]^2- which is green in colour

Question 22.
IUPAC name of CH₃)₂ CH — CH₂ — CH₂Br is
(a) 1-bromopentane
(b) 1-bromo-3-methylbutane
(c) 2-methyl-4-bromobutane
(d) 2-methyl-3-bromopropane
Answer:
(b) 1-bromo-3-methylbutane

Question 23.
The IUPAC name of the compound is

(a) 1 -fluoro-4-methyl-2-nitrobenzene
(b) 4-fIu6ro-lmethyl-3-nitrobenzene
(c) 4-methyl-l-fIuoro-2-nitrobenzene
(d) 2-fIuoro-5-methyl-l-nitrobenzene
Answer:
(d) 2-fIuoro-5-methyl-l-nitrobenzene

Question 24.
The C— O — H angle in ether is about
(a) 180°
(b) 190°28′
(c) 110°
(d) 105°
Answer:
(c) 110°

Question 25.
The C— O — H bond angle in alcohols is slightly less than the tetrahedral angle whereas the C— O — C bond angle in ether is slightly greater because ………
(a) of repulsion between the two bulky R groups.
(b) O atom in both alcohols and ethers is sp³-hybridised
(c) lone pair-lone pair repulsion is greater than bond pair­bond pair repulsion
(d) none of these
Answer:
(a) of repulsion between the two bulky R groups.

Question 26.
Propanone can be prepared from ethyne by
(a) passing a mixture of ethyne and steam over a catalyst, magnesium at 420°C
(b) passing a mixture of ethyne and ethanol over a catalyst zinc chromite
(c) boiling ethyne with water and H₂SO₄
(d) treating ethyne with iodine and NaOH
Answer:
(a) passing a mixture of ethyne and steam over a catalyst, magnesium at 420°C

Question 27.
In the following reaction, product (P) is

(a) RCHO
(b) RCH₃
(c) RCOOH
(d) RCH₂OH
Answer:
(a) RCHO

Question 28.
IUPAC name of the compound (C₂H₅)₂ NCH is
(a) 2, 2-diethylmethanamine
(b) N, N-diethylmethanamine
(c) N-ethyl-N-methylethanamine
(d) N-methylbutanamine
Answer:
(c) N-ethyl-N-methylethanamine

Question 29.
Reduction of aromatic nitro compounds using Sn and HCI gives
(a) armatic primary amines
(b) aromatic secondary amines
(c) aromatic tertiary amines
(d) aromatic amides
Answer:
(a) armatic primary amines

Question 30.
Which of the fol lowing is an example of an aldopentose ?
(a) D-Ribose
(b) Glyceraldehyde
(c) Fructose
(d) Erythrose
Answer:
(a) D-Ribose

Question 31.
Which of the following treatment will convert starch directly into glucose ?
(a) Heating with dilute H₂SO₄
(b) Fermentation by diastase
(c) Fermentation by zymase
(d) Heating with dilute NaOH
Answer:
(a) Heating with dilute H₂SO₄

Question 32.
The correct structure of monomers of buna-S is

Answer:
(c)

Question 33.
The S in buna-S refers to
(a) sulphur
(b) styrene
(c) sodium
(d) salicylate
Answer:
(b) styrene

Question 34.
The main cause of acidity in the stomach is
(a) release of extra gastric acid which decrease the pH level
(b) indidestion and pain in large intestine
(c) increase the pH level in the stomach
(d) release of extra bile juice which increase alkaline medium in stomach.
Answer:
(a) release of extra gastric acid which decrease the pH level

Question 35.
Which of the following will not act as antacid ?
(a) Sodium hydrogen carbonate
(b) Magnesium hydroxide
(c) Sodium carbonate
(d) Aluminium carbonate
Answer:
(c) Sodium carbonate

Non-Objective Type Questions

Short Answer Type Questions

In this Section, there are 18 Short answer type questions (each carrying 2 marks), out of which answer any 10 questions.  2 x 10 = 20

Question 1.
Calculate the osmotic pressure of 5% solution of urea at 272 K . (R = 0.0821 L-atm. deg^-1).
Answer:
As we know that \(\pi=\frac{n_{\text {urea }} R T}{V}\)
Number of moles in urea \(=\frac{5}{60}=0.083\)
Volume of Solution \(=\frac{100}{1000}=0.1\) litres
Hence, Osmotic Pressure, \(\pi=\frac{0.083 \times 0.0821 \times 272}{0.1}=18.53 \mathrm{atm}\)
Osmotic Pressure = 18.53atm

Question 2.
Define standard electrode potential.
Answer:
Standard Electrode Potential : The standard electrode potential is the potential difference between the electrode & electrolyte (at 1 M), at standard conditions (1 atm, 298 K). Standard electrode potential is abbreviated by (E or E°).

Question 3.
What is activation energy ? How is the rate constant of a reaction related to its activation energy ?
Answer:
Activation Energy: The minimum extra amount of energy absorbed by the reactant molecules so that their energy becomes equal to threshold value is called activation energy.
Activation energy (E_a)= Threshold energy (E_T) – Average energy of the reactant (E_R). i.e. E_a = E_T – E_R
If activation energy will be less, then faster will be the reaction.
i. e . Activation energy = \(\alpha \frac{1}{\text { rate of reaction }}\)
e.g. 2NO + O₂ → 2NO₂
It is a fast reaction because of low activation energy. 2CO + O₂ → 2CO₂
It is a slow reaction because of high activation energy.

Question 4.
What is the main difference between physiorption and Chemisorption ?
Answer:
Physisorption:

• Force of attraction are Vander Waal’s forces.
• It usually takes place at low temperature and decreases with increasing temperature.
• It does not require any activation energy.

Chemisorption :

• Force of attraction are chemical bond forces.
• It takes place at high temperature.
• It requires high activation energy.

Question 5.
Differentiate the following giving suitable example:
(i) Calcination and Roasting
(ii) Flux and Slag.
Answer:
(i) Calcination :
(a) Calcination is a thermal treatment process in absence of air applied to ores and materials to bring about a thermal decomposition, phase transition or removal of volalatile fraction It is done at temperature below the melting point of the product material.
(b)

Roasting:
(a) Roasting is reverse process of calcination. It is also thermal process in presence of air applied to ore for removal of volatile fraction under melting point of the product material is called Roasting.
(b)

Flux :
(a) It is chemical cleaning agent, which remove impurities from metal.
(b) Example – CaO + SiO₂ → CaSiO₃

Slag :
(a) Slag is partially vitereous by product of the process of smelting ores, which separates the desiredmetal fraction from the unwanted fraction. It is mixture of metal oxide
(b) Example – CaO + SiO₂ → CaSiO₃

Question 6.
Why do transition elements form coloured compounds ? Explain.
Answer:
The value of electrods potential depends upon the heat of sublimation and ionisation energy
ΔH – ΔH_sub + IE + ΔH_hyd . Due to the influence of ligand d-orbitals of transition metals divide into two unequal energy containing sets. Unpaired electrons absorb sunlight and jumps from one orbit into another orbit and one clour is reflected.

Question 7.
Predict the geometrical shapes of the following:
(a) sp³
(b)d²sp³
Answer:
(a) sp³ tetra-hedral
(b)d²SP³ – Square tetrahedral.

Question 8.
Specify oxidation numbers of the metals in the following co-ordination compounds:
(a) K₄[Fe(CN)₆]
(b) [PtCl₄]^2-
Answer:
(a) Oxidation number of (co-ordination compound)
Let oxidation number of Fe = x
Hence, 1 x 3 + (x -1 x 6 = 0
or, x – 3 = 0
x = 3 = O. N of Fe

(b) Oxidation number of (co-oridnation compaund)
Hence, x + 4 (-1) = – 2
or, x = -2 + 4 = + 2 = ON of Pt

Question 9.
Write the structural formulae of the following:
(a) 4,4 dimethyl-2-pentanol
(b) 2-butanol.
Answer:
(a) 4, 4 dimethyl, 2-Pentanol

Question 10.

Answer:

Question 11.
How will you convert the following ?
(a) Ethyl alcohol to ethylamine
(b) Ethylamine to ethyl alcohol.
Answer:

Question 12.
Explain in which of the following compounds, the chemical bond would have less ionic character: LiCl or KCl.
Answer:
LiCl > KCl – Due to large size of k, KCl compound has less ionic character. LiCl is covalent than Li⁺ has higher polarisation capacity.

Question 13.
Discuss briefly the structure of CsCl.
Answer:
Structure of CsCl.

Question 14.
The osmotic pressure of sugar solution is 2.46 atm at 27°C. Calculate the concentration of the solution.
Answer:

Question 15.
How is molarity of a solution different from molality?
Answer:
Molarity : It is defined as the number of moles of solute dissolved in one liter of solution
\(Molarity (\mathrm{M})=\frac{\text { Moles of solute }}{\text { Volume of Solution in liter }} \)

Molality : It is defined as the number of moles of solute dissolved in one kg of solvent
\(Molality (\mathrm{m})=\frac{\text { Moles of the Solute }}{\text { Mass of the solvent in } \mathrm{kg}}\)

Question 16.
Define heat of neutralisation.
Answer:
Defination of heat of neutralization : The heat reaction resulting from the neutralization of an acid or base especially the quantity produced when a gram equivalent of a base or acid is neutralized with a gram equivalent of an acid or base in dilute soliution.

Question 17.
(a) State law of mass action.
(b) What is the effect of temperature on reaction ?
Answer:
(a) Law of mass action: Law stating that the rate of any chemical reaction is proportional to the product of the masses of the reacting substances, with each mass raised to a power equal to the coefficient that occurs in the chemical equation.

(b) The effect of increasing collision frequency on the rate of the reaction is very minor increasing the temperature increases reaction rates because of the disproportionately large increase in the number of high energy collisions.

Question 18.
Discuss the following terms :
(a) Coordination number
(b) Effective atomic number.
Answer:
(a) The coordination number of a central atom in a molecure or crystal is the number of its near neighbours. This number is determined some what differently for molecules than for crystals.

(b) Effective atomic number has two different meaning; one that is the effective nuclear charge of an atom, and other that calculates the average atomic number for a compound or mixture of materials.

Long Answer Type Questions

There are 06 long answer type questions (each carrying 05 marks), out of which answer any there questions.
(5 x 3 = 15)

Question 19.
Define order to reaction and molecularity of relation. Derive a general expression for specific rate constant of first order reaction.
Answer:
It is the numbers of atom, ion, and molecule that collide with one another simultaneously so as to result into a chemical reaction
Rate constant → It is the speed at which the reactions are converted into the products at any moment of time.
Law of Mass Action → At a given temperature, the rate of a chemical reaction is directly proportional to the product of molar concentrations of reacting species with each concentration term raised to the power equal to numerical co-efficient of that species in the chemical reaction.
Thus, A + B → Products
Rate of reaction, r x [A] [B] = K [A] [B]
Where, [A] and [B] are the molar concentrations of the reactants A and B respectively and K is a constant of proportionality.
∴Rate = K [A]^a [B]^b

First Order Reaction – It is the type of reaction in which the rate of reaction depends only on the first power of the concentration of a single reacting Species.
Let, A + B → Product
If, a be the initial concentration of A and after time t, the concentration of product is x, then the concentration of A left at that instant is (a – x)
A → Products
initial conc._n (a)  ….(i)
after time ‘t’ (a – x)  … (ii)

Where, C → integration constant, which can be obtained from initial condition of the reaction, when, t = 0, x = 0,
then, from (iii) In (a – 0) = K x 0 + C
or, C = In (a)  ………….. (iv)
from (iii) + (iv) – In (a -x) = Kt – In (a)
or, In (a) – In (a – x) = kt or, In (a) – In (a – x) = kt.

Question 20.
(a) Differentiate between DNA and RNA.
(b) What are Nucleic acids ?
Answer:
(a) The structural difference between DNA and RNA
DNA : DNA is double stranded helix in which two strands are coiled spirally in opposite directions.

• The sugar molecule is 2-dehydrobase.
• Nitrogeneous base uracil is not present.
• DNA molecule are very large their molecules weights may vary from 6 million to 16.
• DNA has unique property of replication.

RNA :

• It is single strainded structure.
• The sugar molecules is ribose.
• Nitrogeneous base they-mine is not present.
• RNA molecules are much smaller with molecular weight ranging from 20000 to 40000.
• RNA usually doesn’t replicate.

(b) Nucleic acid – Nucleic acid are found in all living cells in form of nucleo proteins. They constitute important class of biomolecules. Nucleic acids are genetic material of the cells and are responsible for transmission of herediatry effect from one generation to the other and also carry out the biosynthesis of proteins. Nucleic acid are biopolymers (i.e., polymers present in living system). The genetic information about in nucleic acid controls the structure of all proteins including enzymes and thus governs the entire metabolic activity in the living organism.

Question 21.
(a) Discuss the principle involved in the manufacture of sulphuric acid by contact process.
(b) How will you test for sulphate ion ?
Answer:
From following steps sulphuric acid is manufactured
(i) SO₂ gas is produced by burning sulphur of FeS₂ in excess of air
S + O₂  → SO₂
4 FeS₂ +11O₂ → 2Fe₂ O₃ + 8SO₂

(ii) SO₂ is oxidised into SO₃ in prensence of catalyst
2 SO₂ + O₂ → 2 SO₃

(iii) SO₃ on treatment with cone. H₂SO₄ oleum (H₂S₂O₇) is obtained.
SO₃ + H₂SO₄  → 2 H₂S₂2O₇

(iv) From oleum sulphuric acid is obtained of desired concentration by diluting water.
H₂S₂O₇+ H₂O → 2H₂OSO₄

(b) Test of sulphate radical (of NO₂SO₄) – We mix up Barium chloride in the salt. We get white precipate of BaSO₄ which is insoluble in dil. HCl & HNO₃.
BaCl₂ 4- Na₂SO₄ → BaSO₄ ↓ +2 NaCl
BaCl₂ + HNO₃ → In soluble

Question 22.
What are carbohydrates ? How are they classified ?
Answer:
Carbohydrates are the naturally occuring organic compounds and are a major source of energy to our body. In plants carbohydrates are formed as a result for photosynthesis.

In animal systems the carbohydrates undergo decomposition to form carbon-dioxide and water accompanied by the release of energy needed for the body.

Composition of carbohydrates – The chemical formula of the carbohydrates suggests that these are the hydrates of carbon. For example, glucose may be represented as C₆(H₂O)₆ while sucrose as C₁₂(H₂O)₁₁ . But this definition has certain limitation.

(i) Compounds like formaldehyde (CH₂O) and acetic acid (C₂H₄O₂) are the hydrates of carbon do not show characteristics of carbohydrates.

(ii) Similarly, compound like rhammose (C₆H₁₂O₆) and deoxyribose (C₅H₁₀O₄) are carbohydrates but not the hydrates of carbon.

The definition of carbohydrates has been modified and they may be defined as—The polyhydroxy aldehydes or polyhdroxy ketones are substances which generally give these on hydrolysis; contain atleast one chiral carbon and are therefore, opitcally active classification of carbohydrates—

Classification of carbohydrates are done in three way

(a) Based on molecular size – on the basis of the molecular size, carbohydrates have been classified into three types. These are

• Manosaccharides
• Oligosoccharides
• Polysaccharides

Based on taste – Carbohydrates with sweet taste are called sugar while those without a sweet taste are called non-sugars. It may be noted that all mono and oligosaccharides are sugars while polysaccharides are non­sugar.

Reducing and non-reducing sugar –  Carbohydrate which reduce Tollen’s reagent and Fehling solution are called reducing sugar while those which don’t reduce, these are called non reducing sugars. For example – glucose and fructose.

Question 23.
Disuss the following :
(a) Kolbe’s reaction
(b) Wurtz’s reaction
(c) Carbylamine reaction.
Answer:
(a) Kolbe’s reaction – The reaction of phenoxide ion with CO₂ at the high pressure and temperature followed by acidification to form salicylic acid is called Kolbe’s reaction.

(b) Wurtz reaction-When two moles of alkyl halide is heated with Na in the presence of ether goes higher alkane.

(c) Carbylamine reaction-Chloroform when heated with primary amine in presence of alcoholic KOH forms a derivative called isocyanide.

Question 24.
Give one example for each of the following :
(a) Synthetic rubber
(b) Naturally occurring amino acid
(c) Condensation polymer
(d) Additional polymer
(e) Artificial sweeteners.
Answer:
(a) Nioprin
(b) Zwitter ion
(c) NYlon-6, 6
(d) Buna-5
(e) Saccharine.

Bihar Board 12th Physics Model Papers

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

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.
The electric field intensity at distance on the axis of an electric dipole is.Ej and E2 on the perpendicular bisector of dipole. The angle between E] and E2 is 6, will be
(a) 1 : 1, π
(b) 1 : 2, π/2
(c) 2 : 1, π
(d) 1 : 3 π
Answer:
(c) 2 : 1, π

Question 2.
The metre bridge is shown in figure. The value of x is
(a) 10Ω
(b) 3 ohm
(c) 9 ohm
(d) 10 ohm

Answer:
(a) 10Ω

Question 3.
The dimension of electromotive force is
(a) |ML² T^-3]
(b) [ML²T^-3I^-1]
(c) [MLT^-2]
(d) [ML²T^-3I^-1]
Answer:
(d) [ML²T^-3I^-1]

Question 4.
The power of electric circuit is
(a) V.R
(b) V2.R
(c) V2/R
(d) V2RI
Answer:
(c) V2/R

Question 5.
If a 60W and 40W bulb are joined in series the
(a) 60W bulb glow more
(b) 40 W bulb glow more
(c) Both bulb glow similar
(d) Only 60W bulb is lighted
Answer:
(b) 40 W bulb glow more

Question 6.
Kilowatt hour (kwh) is unit of
(a) Power
(b) Energy
(c) Torque
(d) None of these
Answer:
(b) Energy

Question 7.
A magnet is cut parallel to its length in n equal
parts. Magnetic moment of each part will be
\(\text { (a) } \frac{M}{n}\)
\(\text { (b) } \frac{M}{n^{2}}\)
\(\text { (c) } \frac{M}{2 n}\)
(d) None of these
Answer:
\(\text { (a) } \frac{M}{n}\)

Question 8.
The work done to rotate the magnet with 90° will be
(a) MB
(b) MB cosθ
(c) MB sin θ
(d) MB (1 – sin θ)
Answer:
(b) MB cosθ

Question 9.
S.I. unit of polar strength is
(a) Ampere metre
(b) Tesla
(c) Faraday
(d) Ampere gm²
Answer:
(a) Ampere metre

Question 10.
Which is ferromagnetic substance
(a) Mn
(b) Cr
(c) Zn
(d) Alnico
Answer:
(d) Alnico

Question 11.
Which law is based on the principle of conservation of energy?
(a) Lenz’s law
(b) Faraday’s law
(c) Ampere’s law
(d) None of these
Answer:
(a) Lenz’s law

Question 12.
The unit of reactance is
(a) mho
(b) ohm
(c) Faraday
(d) ampere
Answer:
(b) ohm

Question 13.
The phase difference between current and voltage in AC circuit is 0. Then power factor will
(a) cos θ
(b) sin θ
(c) tan θ
(d) 1θ
Answer:
(a) cos θ

Question 14.
The velocity of electro magnetic wave in air is

Answer:
(b)

Question 15.
The light waves are transverse in nature which is shown by
(a) Scattering
(b) Diffraction
(c) Interference
(d) Polarisation
Answer:
(d) Polarisation

Question 16.
When two converging lens of same total length / are placed in contact then focal length combination is
(a) f
(b) 2f
(c) f2
(d) 3f
Answer:
(c) f2

Question 17.
When the light ray passes from one medium to another medium then it is deviated, is called
(a) Dispersion
(b) Refraction
(c) Diffraction
(d) Reflection
Answer:
(b) Refraction

Question 18.
Convex lens are used for
(a) Myopia
(b) Hypermetropia
(c) Old sightedness
(d) Astigmatisn
Answer:
(b) Hypermetropia

Question 19.
The path difference for destructive interference is
(a) nλ
\(\text { (b) }(2 n+1) \frac{\lambda}{2}\)
(c) Zero
(d) infinity
Answer:
\(\text { (b) }(2 n+1) \frac{\lambda}{2}\)

Question 20.
Brewler’s law is
(a) μ = sin i_p
(b) μ = cos i_p
(c) μ = tan i_p
(d) μ = tan² i_p
Answer:
(c) μ = tan i_p

Question 21.
Light is made of vibration by
(a) Ether particle
(b) Air particle
(c) Electric and magnetic field
(d) None of these
Answer:
(c) Electric and magnetic field

Question 22.
Photo cell is based on
(a) photo electric effect
(b) chemical effect of current
(c) magnetic effect of current
(d) electromagnetic cell
Answer:
(a) photo electric effect

Question 23.
Which is uncharged
(a) α-particle
(b) β-particle
(c) photon
(d) proton
Answer:
(c) photon

Question 24.
Lymen series of Hydrogen lies in electromagnetic spectrum is
(a) X : ray
(b) Visible
(c) Infrared
(d) Ultra-violet
Answer:
(d) Ultra-violet

Question 25.
When transition takes place in hydrogen atom from higher orbit to another orbit then obtain
(a) Lymen series
(b) Balmer series
(c) Paschan series
(d) Pfund series
Answer:
(b) Balmer series

Question 26.
The average binding energy per nucleon of nucleus is
(a) 8 ev
(b) 8 Mev
(c) 8 Bev
(d) 8 Joule
Answer:
(b) 8 Mev

Question 27.
The cause of emission of energy in star is
(a) chemical reaction
(b) fusion of heavy nucleus
(c) fusion of light nucleus
(d) fission of heavy nucleus
Answer:
(c) fusion of light nucleus

Question 28.
The Boolean expression of OR gate is
(a) A + B = y
(b) A.B = y
\(\text { (c) } \bar{A}=y\)
\(\text { (d) } \mathrm{C}=\overrightarrow{\mathrm{A} \cdot \mathrm{B}}\)
Answer:
(a) A + B = y

Question 29.
The permeability of Ferromagnetic substance is
(a) μ > 1
(b) μ = 1
(c) μ < 1
(d) μ = 0
Answer:
(a) μ > 1

Question 30.
The light is emitted in forward biased junction diode, is called
(a) LED
(b) Photo diode
(c) Zener diode
(d) None of these
Answer:
(a) LED

Question 31.
Which expression is correct?

Answer:
(d)

Question 32.
The majority carriers in n-type semi conductor is
(a) proton
(b) hole
(c) a-particle
(d) electron
Answer:
(d) electron

Question 33.
Which frequency range is used for TV transmission?
(a) 30 HZ-300HZ
(b) 30 KHZ-300 KHZ
(c) 30 MHZ-300MHZ
(d) 30GHZ-300GHZ
Answer:
(a) 30 HZ-300HZ

Question 34.
Ionosphere is used for radio waves in
(a) rarer mediun
(b) denser medium
(c) free space
(d) dielectric
Answer:
(a) rarer mediun

Question 35.
The maximum distance upto which TV signal can be received from Antenna of height h is proportional to
(a) h^1/2
(b) h
(c) h^5/2
(d) h²
Answer:
(a) h^1/2

Non-Objective Type Questions!
Short Answer Type Questions

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

Question 1.
Electric lines of force never intersect to each other. Why?
Answer:
If two lines of force intersect at a point then it will mean that at that point electric field has two directions. As it is not possible, the lines of force here not intersect to each other.

Question 2.
Write the limitations of Coulomb’s law.
Answer:
Coulomb’s law in electrostatics does not hold in all situation. It is applicable only in following situations :

1. The electric charges must be stationary.
2. The electric charge must be point in size. Coulomb’s law doesn’t apply to two charged bodies of finite size. It is because, the distribution of charge doesn’t remain uniform when the two bodies are brought together.

Question 3.
Prove maximum power theorem.
Answer:
It states that the output power of a source of emf is maximum, when the external resistance in the circuit is equal to the internal resistance of the source.

This is maximum power theorem.

Question 4.
Establish the relation b/w current density and drift velocity.
Answer:

Question 5.
What is Hysteresis loop? With its help explain the terms retentivity and co-ercivity.
Answer:
Hysteresis loop : Hysteresis loop is defined as the lagging of the magnetic induction B behind the corresponding magnetic field H.

When magnetic field H and the magnetic induction B are yarned from zero to maximum in one direction and then back through zero to a maximum in the opposite direction and finally back again through zero to the first maximum, a cycle of magnetisation is said to be completed. B(T) Y Using the value of H and B obtained above, we plot a graph by taking H along x-axis and B along y-axis. When the magnetic field H is increased from zero to the maximum value Og, the induction B follows the curve Oa. However, when the magnetic field is brought to zero, the.;induction does not follows back the curve Oa but a different curve ab. The same pattern of variations is seen for the rest of the curve. The B-H curve for decreasing H does not coincide with the B-H curve for increasing H.

As is clear from figure, even when the magnetising field H is zero, some magnetic induction (Ob or Oe) is still present in the speci nen. It is denoted by Br and is called remanance or retent i vity or residual magnetism.

The value of the intensity of magnetisation of a material when the magnetisi ng field is reduced to zero is called retentivity.

After the specimen has been magnetised to saturation (oh or oj) a reversed magnetising field (equal to Oc or Of) is required to reduce the magnetic induction to zero.This is called the coercivity or coercive force He. The value of the magnetising field required to reduce residual magnetism to zero is called coercivity of the material.

Question 6.
Write the expression for energy stored in the
Answer:
The induced emf in coil \(e=-L \frac{d I}{d t}\)
let chasge dq passes from coil, the work done dw = e.dq
\(\begin{aligned}
&=\mathrm{L} \cdot \frac{d I}{d t} d q=\mathrm{L} \cdot d I \cdot \frac{d q}{d t} \\
d w &=\mathrm{LI} . \mathrm{dI}
\end{aligned}\)

work done after posting current O to 1
\(\omega=\mathrm{L} \int_{0}^{1} I d I=\mathrm{L}\left[\frac{I^{2}}{2}\right]_{0}^{1} ; \omega=\frac{1}{2} \mathrm{L}^{2}\)

This work done is stored in the potential energy of coil.
\(P \cdot E=\frac{1}{2} L I^{2}\)

Question 7.
What is current sensitivity and voltage sensitivity of moving coil galvanometer?
Answer:
Current sensitivity : It is defined as the deflection produced in the galvanometer, when a unit voltage is applied across its cops.
\(\frac{\alpha}{\mathrm{I}}=\frac{\mathrm{nBA}}{\mathrm{K}}\)

Voltage sensitivity : It is defined as the deflection produced in the galvanometer, when a unit voltage is applied across its COPI.
\(\frac{\alpha}{V}=\frac{n B A}{K R}\)

Question 8.
Write the expression for energy density related with electro magnetic wave and show that its ratio is equal to 1.
Answer:

Question 9.
Sketch the wave front corresponding to (a)
diverging rays and (b) converging rays.
Answer:

Question 10.
Write the differences between magnification and magnifying power.
Answer:
Magnification :

• It is a linear magnification which is equal to \(\frac{n_{2}}{n_{1}}\).
• Its value increases with increase in V.
• It may be between to -∞ to +∞.
• Under certain conditions it is equal to magnifying power.

Magnifying power :
(i) It is an angular magnification which is equal to \(\frac{\angle \beta}{\angle \alpha}\)
(ii) Its value decreases with increase in V.
(iii) Its value may be b/w \(\frac{d}{f}\) and \(\left(1+\frac{D}{f}\right)\)
(iv) It is a special condition of magnification when (v_e = D

Question 11.
Derive the expression for de-Broglie wave length.
Answer:
A/C to quantum theory E = hv ……………………….. (i)

λ is called de-Broglie wavelength.

Question 12.
What is mass defect?
Answer:
Mass defect : The difference b/w sum of the masses of neutrons and protons forming a nucleus and actual mass of the nucleus is called mass defect.
Δm = [mpz + m_n (A – Z) – M]
The unit of mass defect is amu.

Question 13.
Why does thermionic emission takes place from metal surface only?
Answer:
Thermionic emission takes place from metal surface only because metal has free electrons on its surface.This free electrons requires less energy to come out from one surface. Also sometimes, to reduce work function of metal by coating oxide layer on metal.

Question 14.
Why is semi conductor damaged by a strong current?
Answer:
A strong current, when passed through a semi conductor, heat up the semi conductor and covalent bond break up. It results in a large number of free electrons. The material behaves as a conductor. As now the semi conductor no longer possesses the property of conduction, it is said to be damaged.

Question 15.
Write the differences between Intrinsic and extrinsic semi conductor.
Answer:
Intrinsic semi conductor :

• They are the crystals of pure elements like Germanium and Silicon.
• n_e = n_h
• The electrical conductivity of Intrinsic semi conductor is low.
• Resistivity is higher.

Extrinsic semi conductor:

• When some impurity is added in Intrinsic semi conductor, we get an extrinsic semi conductor.
• n_e ≠ n_h
• Its electrical conductivity is high.
• Resistivity is lower.

Question 16.
Define mean value and root square value A.C. Write its expression.
Answer:
Mean value of Average value : It is that steady current when passes through the circuit for half time period, sends the same amount of charge of the alternating current, sends the charge in same circuit and in same time period. It is denoted by Im.
\(\begin{aligned}
&I_{m}=\frac{2 I_{0}}{\pi}\\
&I_{m}=0.636 I_{0}
\end{aligned}\)

R.M.S. value or virtual value: It is that steady current when passes through the circuit for half time period, produces the same amount of heat as the alternating current produces the heat in same time and in same circuit. It is denoted by Irms.
\(\begin{aligned}
&I_{r m s}=\frac{I_{0}}{\sqrt{2}}\\
&I_{r m s}=0.7071
\end{aligned}\)

Question 17.
What is polaroids? Write its important uses.
Answer:
It is a device which produces plane polarised light. Use of polaroids :

• Sun glasses fitted with polaroid sheets protect the eye from glass.
• Wind shields of automobiles are also made of Polaroid sheets.
• They are useful in three dimensional motion pictures.
• It is used in L.C.D., calculator, watches, T.V. etc.

Question 18.
Write the condition for sustained interference.
Answer:
Condition for sustained interference :

• The two source should emf the light wave continuously.
• The light wave should be of same wave length.
• The two light source should be narrow.
• The light waves emitted should be of the same amplitude.
• The two source of light must lie very close to each other.

Long Answer Type Questions

Question 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.
Explain any two of the following terms :
(i) Ground Waves
(ii) Sky Waves
(iii) Space Waves.
Answer:
(i) Ground Waves : The ground waves which progress along the surface of the earth are called ground waves or surface waves. The ground propagation is suitable for low and medium frequency, i.e., up to 2 MHz only, hence it is also called medium wave propagation: The maximum range of ground or surface wave propagation depends on :

• The frequency of the radio waves and
• Power of the transmitter.

(ii) The Sky Waves : The sky waves are the radio waves of frequency between 2 MHz to 30 MHz. The ionosphere reflects those radio waves so that they can propagate through atmosphere. The sky waves propagation is also known as ionosphere propagation.

The sky waves are used for very long distance radio communication at medium high frequencies (i.e. at medium waves and short waves). The radio waves can cover a distance approximately 400 km in a single reflection from the ionosphere.

(iii) Space Waves : The space waves are the radio waves of very high frequency (i.e. between 30 MHz to 300 MHz or more). The space waves can travel through atmosphere from transmitter antenna to receive antenna either directly or after reflection from ground in the earth’s troposphere region. It is also called Tropospherical propagation or line of sight propagation. This propagation is limited (a) to the line of sight distance, (b) by the curvature of the earth.

It is utilized in T.V. communication, Radar communication, etc.

Question 20.
Find an expression for the electric field strength at a distant point situated (i) on the axis and (ii) along the equatorial line of an electric dipole.
Answer:
Consider an electric dipole AB. The charges -q and +q of dipole are situated at A and B respectively. The separation between the charges is 21.

Electric dipole moment, p = Q 21
The direction of dipole moment is from -q to + Q

(i) At axial or end-on position : Consider a point P on the axis of dipole at a distance r from mid-point O of electric dipole.

The distance of point P from charge + q is BP = r – l and distance of point P from charge – q is, AP = r + l. Let E₁ and E₂ be the electric field strengths at point P due to charges +<7 and -q respectively. We know that the direction of electric field due to a point charge is away from positive charge and towards the negative charge. Therefore

Clearly the directions of electric field strengths \(\overrightarrow{\mathrm{E}}_{1}\) and \(\overrightarrow{\mathrm{E}}_{2}\) are along the same line but opposite to each other and E₁ > E₂ because positive charge is nearer.

∴ The resultant electric field due to electric dipole has magnitude equal to the difference of E₁ and E₂ and direction from 13 to P i.e.

If the dipole is infinitely small and point P is far away from the dipole, then r >> l, therefore equation (i) may be expressed as
\(\mathrm{E}=\frac{1}{4 \pi \varepsilon_{0}} \frac{2 p r}{r^{4}} \text { or } \mathrm{E}=\frac{1}{4 \pi \varepsilon_{0}} \frac{2 p}{r^{3}}\) …………………………… (ii)

This is the expression for the electric field strength at axial position due to a short electric dipole.

Question 21.
Explain the principle and working of a Cyclotron with the help of a neat diagram. Write the expression for Cyclotron frequency.
Or,With the help of a labelled diagram, state the underlying principle of a Cyclotron. Explain clearly how it works to accelerate the charged particles.

Show that Cyclotron frequency is independent of energy of the particle. Is there an upper limit on the energy acquired by the particle? Give reason.
Answer:
(a) Cyclotron : The cyclotron, devised by Lawrence and Livingston, is a device for accelerating ions to high speed by the repeated application of accelerating potentials.

Construction:
The cyclotron consists of two flat semi-circular metal boxes called ‘dees’ and are arranged with a small gap between them. A source of ions is located near the mid-point of the gap between the dees (fig). The dees are connected to the terminals of a radio frequency oscillator, so that a high frequency alternating potential of several million cycles per second exists between the dees. Thus dees act as electrodes. The dees are enclosed in an insulated metal box containing gas at low pressure. The whole apparatus is placed between the poles of a strong electro¬magnet which provides a magnetic field perpendicular to the plane of the dees.

Working :
The principle of action of the apparatus is shown in fig.The positive ions produced from a source S at the centre are accelerated by a dees which is at negative potential at that moment. Due to the presence of perpendicular magnetic field the ion will move in a circular path inside the dees. The magnetic field and the frequency of the applied voltages are so chosen that as the ion comes out of a dees, the dees change their polarity (positive becoming negative and vice-versa) and the ion is further accelerated and moves with high velocity along a circular path of greater radius. The phenomenon is continued till the ion reaches at the periphery of the deeS where an auxiliary negative electrode (deflecting plate) deflects the accelerated ion on the target to be bombarded.

The function of electric field is to accelerae the charged particle and so to impart energy to the charged particle.

The function of magnetic field is to provide circular path to charged particle and so to provide the location where charged particle is capable of gaining energy from electric field.

Expression for Period of Revolution and Frequency :

Suppose the positive ion with charge q moves in a dees with a velocity v, then,
\(q v \mathrm{B}=\frac{m v^{2}}{r} \text { or }=\frac{m v}{q \mathrm{B}}\) …………………………… (i)

where m is the mass and r is the radius of the path of ion in the dees and B is the strength of the magnetic field. The angular velocity to of the ion is given by.
\(\omega=\frac{v}{r}=\frac{q \mathrm{B}}{m}( \text { from eq. }\) ………………… (ii)

The time taken by the ion in describing a semi-circle, i.e., in turning through an angle π is.
\(t=\frac{\pi}{\omega}=\frac{\pi m}{\mathrm{B} q}\)

Thus the time is independent of the speed of the ion i.e., although the speed of the ion goes on increasing with increase in the radius (from eQuestion i) when it moves from one dees to the other, yet it take the same time in each dees.

From eQuestion (iii) it is clear that for a particular ion, \(\frac{m}{q}\)

being known, B can be calculated for producing resonance with the high frequency alternating potential.

(b) Resonance Condition : The condition of working of cyclotron is that the frequency of radio frequency alternating potential must be equal to the frequency of revolution of charged particles within the dees. This is called resonance condition.

Now for the cyclotron to work, the applied alternating potential should also have the same semiperiodic time (T/2) as that taken by the ion to cross either dees, i.e.,

This is the expression for period of revolution. Obviously, period of revolution is independent of speed of charged particle and radius of circular path.

∴ Frequency of revolution of particles.
\(f=\frac{1}{T}=\frac{q B}{2 \pi m}\)

This frequency is called the cyclotron frequency. Clearly the cyclotron frequency is independent of speed of particle.

(c) Expression for K.E. attained : If R be the radius of the path and Vmax, the velocity of the ion when it leaves the periphery, then in accordance with eq (ii)
\(v_{\max }=\frac{q \mathrm{BR}}{m}\) …………………………….. (vi)

The kinetic energy of the ion when it leaves the apparatus is,
\(\text { K.E. }=\frac{1}{2} m v^{2} \max =\frac{q^{2} B^{2} R^{2}}{2 m}\) ………………….. (vii)

When charged particle crosses the gap between dees it gains KE = qV

In one revolution, it crosses the gap twice, therefore if it completes ^-revolutions before emerging the dees, the kinetic energy gained = 2nqV ………………. (viii)
\(\text { Thus, K.E. }=\frac{g^{2} \mathrm{B}^{2} \mathrm{R}^{2}}{2 m}=2 n q \mathrm{V}\)

Question 22.
Using Ampere’s circuital law, derive an expression for the magnetic field along the axis of a toroidal solenoid.
Answer:
Magnetic field due to a toroidal solenoid : A long solenoid shaped in the form of closed ring is called toroidal solenoid (or endless solenoid). Let n be the number of turns per unit of toroid and I the current flowing through it. The current causes the magnetic field inside the turns of the solenoid. The magnetic lines of force inside the toroid are in the form of concentric circle. By symmetry of the magnetic field it has the same magnitude at each point of circle and is along the tangent at every point on the circle.

For points inside the core of toroid: Consider a circle of radius r in the region enclosed by turns of toroid. Now we apply Ampere’s circuital law to this circular path, i.e.,
\(\vec{f} \overrightarrow{\mathrm{B}} \cdot \overrightarrow{d l}=\mu_{0} I\) ………………. (i)

\(\vec{f} \overrightarrow{\mathrm{B}} \cdot \overrightarrow{d l}=f B d l \cos 0=B \cdot 2 \pi r\) Length of toroid = 2πr Number of turns in toroid = n (2πr) and current in one- turn = I.

∴ Current enclosed by circular path = (n 2πr) • 1
∴ Equation (i) gives
\(\mathrm{B} 2 \pi r=\mathrm{m}_{0}(n 2 \pi r l) \Rightarrow \mathrm{B}=\mu_{0} n \mathrm{l}\)

Derivation of formula for magnetic field due to a current carrying wire using Biot-Savart law : Consider a wire EF carrying current I in upward direction. The point of observation is P at a finite distance R from the wire. If PM is perpendicular dropped from P on wire; then PM = R. The wire may be supposed to be formed of a large number of small current elements. Consider a small element CD of length δf at a distance f from M.

\(\text { Let } \angle \mathrm{CPM}=\phi \text { and } \angle \mathrm{CPD}=\delta \phi, \angle \mathrm{PDM}=\theta\) The length δf is very small, so that ∠PCM may also be taken as equal to θ.

The perpendicular dropped from C on PD is CN.

The angle formed between element I \(\overrightarrow{\delta l}\) and \(\overrightarrow{r}\) (= cp is (π – θ), Therefore according to Biot-Savart law, the magnetic field due to current element I \(\overrightarrow{\delta l}\) at P is

If the wire is of finite length and its ends make angles a and p with line MP, then net magnetic field (B) at P is obtained by summing over magnetic fields due to all current elements, i.e.,

This is expression for magnetic field due to current carrying wire of finite length (or very long), then α = β ⇒ π/2.

Question 23.
Draw the labelled ray diagram for the formation of image by a compound microscope.
Derive an expression for its total magnification (or magnifying power), when the find image is formed at the near point.
Why both objective and eye piece of a compound microscope must have their short focal lengths?
Answer:
Compound Microscope :
It consists of a long cylindrical tube, containing at one end of a convex lens of small aperture and small focal length. This is called the objective lens (O). At the other end of the tube another co¬axial smaller and wide tube is fitted which carries a convex lens (E) at its outer end. This lens is towards the eye and is called the eye-piece. The focal length and aperture of eye piece are somewhat large than those of objective lens. Cross¬wires are mounted at a definite distance before the eye piece. The entire tube can be moved forward and backward by the rack and pinion arrangement.

Magnifying power of a microscope:
is defined as the ratio of angle ((3) subtended by final image on the eye to the angle (a) subtended by the object on eye, when the object is placed at the least distance of distinct vision, i.e.,

Magnifying power \(M=\frac{\beta}{\alpha}\)

As object is very small, angles α and β are very small and so tan α = α and tan β = β. By  efinition the object AB is placed at the least distance of distinct vision

Question 24.
State the principle of working of p-n diode as a rectifier. Explain with the help of a circuit diagram, the use of p-n diode as full wave rectifier. Draw a sketch of the input and output wave forms. Or, Draw a circuit diagram of a full wave rectifier. Explain the working principle. Draw the input/output wave forms indicating clearly the functions of the two diodes used.
Answer:
Rectification :
Rectification means conversion of a.c. into d.c. A p-n diode acts as a rectifier because an ac changes polarity periodically and a p-n diode conducts only when it is forward biased; it does not conduct when reverse biased.

In a full wave rectifier, if input frequency is / hertz, then output frequency will be 2/ hertz because for each cycle of input, two positive half cycles of output are obtained.

Working:
The AC input voltage across secondary s₁ and s₂ cli anges polarity after each half cycle. Suppose during the first half cycle of input AC signal, the terminal s₁ is positive relative to centre tap O and s₂ is negative relative to O. Then diode D₁ is forward biased and diode D₂ is reverse biased. Therefore diode D₁ conducts while diode D₂ does not. The direction of current (i₁) due to diode D₁ in load rsistance R_L is directed from A to 13. In next half cycle, the terminal s is negative and s₂ is positive relative to centre tap O.

The diode D is reverse biased and diode D₂ is forward biased. Therefore, diode D₂ conducts while D₁ does not. The direction of current (i₂) due to diode D₂ in load resistance R_L is still from A to B. Thus the current in load resistance R_L is in the same direction for both half cycles of input AC voltage. Thus for input AC signal the output current is a continuous series of unidirectional pulses.

In a full wave rectifier, if input frequency is f hertz, then output frequency will be 2f hertz because for each cycle of input, two positive half cycles of output are obtained.

Bihar Board 12th Biology Objective Questions and Answers

Bihar Board 12th Biology Objective Answers Chapter 1 Reproduction in Organisms

Question 1.
Single-celled animals are said to be immortal because
(a) they grow indefinitely in size
(b) they can tolerate any degree of change in temperature
(c) they can reproduce throughout their life span
(d) they continue to live as their daughter cells.
Answer:
(d) they continue to live as their daughter cells.

Question 2.
Which of the following has the longest life span?
(a) Banyan tree
(b) tortoise
(c) parrot
(d) Elephant
Answer:
(a) Banyan tree

Question 3.
Select the option which arranges the given organisms in ascending order of their life span.
(a) Parrot < Crow < Butterfly < Banyan tree
(b) Butterfly < Crow < Parrot < Crocodile
(c) Fruit fly < Crocodile < Parrot < Banyan tree
(d) Parrot < Tortoise < Dog < Crow
Answer:
(c) Fruit fly < Crocodile < Parrot < Banyan tree

Question 4.
________ is a life process that is not essential for an individual’s survival but for survival of the species.
(a) Growth
(b) Reproduction
(c) Respiration
(d) Nutrition
Answer:
(b) Reproduction

Question 5.
‘Clones’ are individuals that have exactly the same
(a) Lifespan
(b) physiology
(c) growth rate
(d) genetic makeup.
Answer:
(d) genetic makeup.

Question 6.
Which one of the following processes results in the formation of clone of bacteria?
(a) Regeneration
(b) Budding
(c) Binary fission
(d) Fragmentation
Answer:
(c) Binary fission

Question 7.
Asexual reproduction is seen in members of Kingdom
(a) Monera
(b) Plantae
(c) Animalia
(d) All of these.
Answer:
(d) All of these.

Question 8.
During binary fission in Amoeba which of the following organelles is duplicated?
(a) Plasma membrane
(b) Nucleus
(c) Contractile
(d) All of these
Answer:
(b) Nucleus

Question 9.
Vegetative propagation is the term used for
(a) sexual reproduction in animals
(b) sexual reproduction in plants
(c) asexual reproduction in animals
(d) asexual reproduction in plants.
Answer:
(d) asexual reproduction in plants.

Question 10.
Which of the following is not used for vegetative propagation?
(a) Bud
(b) Bulbil
(c) Turion
(d) Antherozoid
Answer:
(d) Antherozoid

Question 11.
Identify the given organism and find its maximum life span.

(a) Sparrow, 25 years
(b) Crow, 30 years
(c) Crow, 15 years
(d) Eagle, 40 years
Answer:
(c) Crow, 15 years

Question 12.
Which of the following options shows two plants in which new plantlets arise from the same organ?
(a) Dahlia and ginger
(b) Potato and sweet potato
(c) Dahlia and rose
(d) Potato and sugarcane
Answer:
(d) Potato and sugarcane

Question 13.
Refer to the given figure and identify X in it.

(a) Offset
(b) Eyes
(c) Runner
(d) Bulb
Answer:
(b) Eyes

Question 14.
Fleshy buds produced in the axil of leaves, which grow to form new plants when shed and fall on ground, are called
(a) bulbs
(b) bulbils
(c) tubers
(d) offsets.
Answer:
(b) bulbils

Question 15.
In which one pair, both the plants can be vegetatively propagated by leaf pieces?
(a) Bryophyllum and Kalanchoe
(b) Chrysanthemum and Agave
(c) Agave and Dioscorea
(d) Bryophyllium and Asparagus
Answer:
(a) Bryophyllum and Kalanchoe

Question 16.
Identify the given vegetative propagule.

(a) Bulb
(b) Runner
(c) Rhizome
(d) Bulbil
Answer:
(d) Bulbil

Question 17.
If a leaf cell of Agave has x chromosomes then what will
be the number of chromosomes in a cell of its bulbil?
(a) 2 x
(b) x/2
(c) x/4
(d) x
Answer:
(d) x

Question 18.
Which of the following cannot serve as a vegetative propagule?
(a) A piece of potato tuber with eyes
(b) A middle piece of sugarcane internode
(c) A piece of ginger rhizome
(d) A marginal piece of Bryophyllum leaf
Answer:
(b) A middle piece of sugarcane internode

Question 19.
Which of the following options correctly identifies artificial and natural methods of vegetative propagation?
Artificial methods – Natural methods
(a) Grafting – Cutting
(b) Layering – Bulbils
(c) Offset – Tissue culture
(d) Tubers – Rhizomes
Answer:
(b) Layering – Bulbils

Question 20.
Sexual reproduction is considered more beneficial than asexual reproduction because
(a) it is not affected by adverse environmental conditions
(b) fertilization is a chance factor
(c) it rapidly multiplies the population
(d) it assists in evolution by producing variations.
Answer:
(d) it assists in evolution by producing variations.

Question 21.
The growth phase of an organism before attaining sexual maturity is referred to as
(a) juvenile phase
(b) vegetative phase
(c) both (a) and (b)
(d) none of these.
Answer:
(c) both (a) and (b)

Question 22.
Select the monocarpic plant out of the following.
(a) Bamboo
(b) Lite hi
(c) Mango
(d) All of these
Answer:
(a) Bamboo

Question 23.
Clear cut vegetative, reproductive and senescent phases cannot be observed in
(a) annual plants
(b) perennial plants
(c) biennial plants
(d) ephemeral plants.
Answer:
(b) perennial plants

Question 24.
Strobilanthus kunthiana flowers once in
(a) 5 years
(b) 12 years
(c) 20 years
(d) 50 years.
Answer:
(b) 12 years

Question 25.
Strobilanthus kunthiana differs from bamboo in
(a) being monocarpic
(b) length of juvenile phase
(c) being polycarpic
(d) none of these.
Answer:
(b) length of juvenile phase

Question 26.
Oestrous cycle is reported in
(a) cows and sheep
(b) humans and monkeys
(c) chimpanzees and gorillas
(d) none of these.
Answer:
(a) cows and sheep

Question 27.
Which of the following animals show menstrual cycle ?
(a) Gorillas and chimpanzees
(b) Monkeys and humans
(c) Orangutans and monkeys
(d) All of these
Answer:
(d) All of these

Question 28.
Senescent phase of an organism’s life span can be recognised by
(a) slow metabolism
(b) cessation of reproduction
(c) decreased immunity
(d) all of these
Answer:
(d) all of these

Question 29.
If a fungal thallus has both male and female reproductive structures, it will be called
(a) heterothallic
(b) homothallic
(c) dioecious
(d) monoecious
Answer:
(b) homothallic

Question 30.
Staminate flowers produce
(a) eggs
(b) antherozoids
(c) fruits
(d) all of these
Answer:
(b) antherozoids

Question 31.
Which of the following is a unisexual organisam?

Answer:

Question 32.
Which of the following groups is formed only of the hermaphrodite organisms?
(a) Earthworm, tapeworm, housefly, frog
(b) Earthworm, tapeworm, sea horse, housefly
(c) Earthworm, leech, sponge, roundworm
(d) Earthworm, tapeworm, leech, sponge
Answer:
(d) Earthworm, tapeworm, leech, sponge

Question 33.
Which of the following options shows bisexual animals only?
(a) Amoeba, sponge, leech
(b) Sponge, cockroach, Amoeba
(c) Earthworm, sponge, leech
(d) Tapeworm, earthworm, honeybee
Answer:
(c) Earthworm, sponge, leech

Question 34.
Read the following statements and select the incorrect one.
(a) Cucurbits and coconuts are monoecious plants.
(b) Papayas and date palms are dioecious plants.
(c) Leeches and tapeworms are bisexual animals.
(d) Sponges and coelenterates are unisexual animals.
Answer:
(d) Sponges and coelenterates are unisexual animals.

Question 35.
Meiosis does not occur in
(a) asexually reproducing diploid individuals
(b) sexually reproducing haploid individuals
(c) sexually reproducing diploid individuals
(d) all of these.
Answer:
(a) asexually reproducing diploid individuals

Question 36.
A diploid parent plant body produces ________ gametes and a haploid parent plant body produces ________ gametes.
(a) diploid, haploid
(b) haploid, diploid
(c) diploid, diploid
(d) haploid, haploid
Answer:
(d) haploid, haploid

Question 37.
Which of the following organisms has the highest number of chromosomes?
(a) Housefly
(b) Butterfly
(c) Ophioglossum
(d) Onion
Answer:
(c) Ophioglossum

Question 38.
In maize, a meiocyte has 20 chromosomes. What will be the number of chromosomes in its somatic cell?
(a) 40
(b) 30
(c) 20
(d) 10
Answer:
(c) 20

Question 39.
If a butterfly has chromosome number 360 in its meiocyte (2n). What will be the chromosome number in its gametes?
(a) 380
(b) 190
(c) 95
(d) 760
Answer:
(b) 190

Question 40.
In flowering plants, both male and female gametes are non-motile. The method to bring them together for fertilisation is
(a) water
(b) air
(c) pollination
(d) apomixis
Answer:
(c) pollination

Question 41.
Development of new individual from female gamete without fertilisation is termed as
(a) syngamy
(b) embryogenesis
(c) oogamy
(d) parthenogenesis.
Answer:
(d) parthenogenesis.

Question 42.
Fertilisation cannot occur in absence of surface water in
(a) Fucus
(b) Funaria
(c) Marsilea
(d) all of these.
Answer:
(d) all of these.

Question 43.
Spirogyra is a sexually reproducing alga in which vegetative thallus is haploid. In Spirogyra, meiosis
(a) never occurs
(b) occurs at time of gamete production
(c) occurs after fertilisation
(d) occurs during vegetative growth.
Answer:
(c) occurs after fertilisation

Question 44.
Life begin in all sexually reproducing organisms as a
(a) single-celled zygote
(b) double-celled zygote
(c) haploid zygote
(d) haploid gametes.
Answer:
(a) single-celled zygote

Question 45.
Which of the following is not correct regarding sexual reproduction ?
(a) It is usually biparental.
(b) Gametes are always formed.
(c) It is a slow process
(d) It involves only mitosis.
Answer:
(a) It is usually biparental.

Question 46.
Offsprings of oviparous animals are at greater risk of survival as compared to those of viviparous animals because
(a) proper embryonic care and protection is absent
(b) embryo does not develop completely
(c) progenies are of smaller size
(d) genetic variations do not occur.
Answer:
(a) proper embryonic care and protection is absent

Question 47.
Deposition of calcareous shell around zygote occurs in
(a) birds and reptiles
(b) birds and mammals
(c) mammals and reptiles
(d) all of these.
Answer:
(a) birds and reptiles

Question 48.
Select the option which shows viviparous animals only,
(a) Lizard, Turtile
(b) Platypus, Crocodile
(c) Cow, Crocodile
(d) Whale, Mouse
Answer:
(d) Whale, Mouse

Question 49.
Which of the following animals give birth to young ones?
(a) Ornithorhynchus and Echidna
(b) Macropus and Pteropus
(c) Balaenoptera and Homo sapiens
(d) Both (a) and (c)
Answer:
(d) Both (a) and (c)

Question 50.
Viviparity is found in
(a) Sharks
(b) lizards
(c) frogs
(d) birds
Answer:
(a) Sharks

Question 51.
In which of the following plants, sepals do not fall off after fertilisation and remain attached to the fruit?
(a) Brinjal
(b) Cucumber
(c) Papaya
(d) Bitter gourd
Answer:
(a) Brinjal

Question 52.
Which of the labelled parts in the transverse section of tomato fruit, is/are diploid?

(a) X
(b) Y
(c) Both X and Y
(d) None of these
Answer:
(c) Both X and Y

Question 53.
The wall of the ovary forms
(a) pericarp
(b) fruit wall
(c) fruit
(d) both (a) and (b).
Answer:
(d) both (a) and (b).

Question 54.
The term ‘clone’ cannot be applied to offspring formed by sexual reproduction because
(a) offspring do not possess exact copies of parental DNA
(b) DNA of only one parent is copied and passed on to the offspring
(c) offspring are formed at different times
(d) DNA of parent and offspring are completely different
Answer:
(a) offspring do not possess exact copies of parental DNA

Question 55.
The male gametes of rice plant have 12 chromosomes in their nucleus. The chromosome number in the female gamete, zygote and the cells of the seedling will be, respectively
(a) 12,24,12
(b) 24,12,12
(c) 12, 24, 24
(d) 24, 12, 24.
Answer:
(c) 12, 24, 24

Question 56.
Appearance of vegetative propagules from the nodes of plants such as sugarcane and ginger is mainly because
(a) nodes are shorter than intemodes
(b) nodes have meristematic cells
(c) nodes are located near the soil
(d) nodes have non-photosynthetic cells.
Answer:
(b) nodes have meristematic cells

Question 57.
There is no natural death in single celled organisms like Amoeba and bacteria because
(a) they cannot reproduce sexually
(b) they reproduce be binary fission
(c) parental body is distributed among the offspring
(d) they are microscopic.
Answer:
(c) parental body is distributed among the offspring

Question 58.
There are various types of reproduction. The type of reproduction adopted by an organism depends on
(a) the habitat and morphology of the organism
(b) morphology of the organism
(c) morphology and physiology of the organism
(d) the organisms habitat, physiology and genetic makeup.
Answer:
(d) the organisms habitat, physiology and genetic makeup.

Question 59.
Which of the following is a post-fertilisation event in flowering plants?
(a) Transfer of pollen grains
(b) Embryo development
(c) Formation of flower
(d) Formation of pollen grains
Answer:
(b) Embryo development

Question 60.
The number of chromosomes in the shoot tip cells of a maize plant is 20. The number of chromosomes in the microspore mother cells of the same plant shall be
(a) 20
(b) 10
(c) 40
(d) 15
Answer:
(a) 20

Bihar Board 12th Biology Model Papers

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

Time : 3 Hours 15 Min
Total Marks : 70

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 indicate full marks.
3. While answering the questions, the candidate should adhere to the word limit as for as practicable.
4. 15 Minutes of extra time has been allotted for the candidates 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 result will be treated as invalid.
7. In Section – B, there are Non-objective type questions. There are 18 Short answer type questions, out of which any 10 questions are to be answered. Each question carries 2 marks. Apart from this, there are 6 long answer type questions, out of which any 3 of them are to be answered. Each question carries 5 marks
8. Use of any electronic device is prohibited.

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.
Pollination by birds is called
(a) Entomophily
(b) Cheiropterophily
(c) Ornithophily
(d) All of the above
Answer:
(c) Ornithophily

Question 2.
Which one is the hotspot of biodiversity?
(a) Eastern Ghat
(b) Western Ghat
(c) Aravalli Hills
(d) None of the above
Answer:
(b) Western Ghat

Question 3.
Who is considered as Father of Genetics?
(a) Morgan
(b) Darwin
(e) Hugo-de-Vries
(d) Mendel
Answer:
(d) Mendel

Question 4.
Noise pollution is measured in
(a) Heartz
(b) Fathoms
(c) Decibels
(d) Nanometer
Answer:
(c) Decibels

Question 5.
Indicator of water pollution is
(a) Entamoeba histolytica
(b) E. Coli
(c) Vibrio cholera
(d) All of the above
Answer:
(b) E. Coli

Question 6.
mRNA formation takes place in
(a) Ribosome
(b) Nucleus
(c) Cytoplasm
(d) Mitochondria
Answer:
(b) Nucleus

Question 7.
Cancer affecting connective tissue is called
(a) Lymphoma
(b) Sarcoma
(c) Carcinoma
(d) None of the above
Answer:
(b) Sarcoma

Question 8.
IgM antibody is found in
(a) Serum
(b) Saliva
(c) Blood
(d) All of the above
Answer:
(c) Blood

Question 9.
How many Peptide chains are found in each antibody molecule?
(a) 4
(b) 3
(c) 2
(d) None of the above
Answer:
(a) 4

Question 10.
Green plants are known as producers, which convert
(a) Chemical energy into light energy.
(b) Light energy into chemical energy
(c) All of the above
(d) None of the above
Answer:
(b) Light energy into chemical energy

Question 11.
Which of the following cry gene prevents crop from borer
(a) Cry AC
(b) Cry / Ab
(c) Cry // Ab
(d) All of the above
Answer:
(d) All of the above

Question 12.
Human blood groups are
(a) A, B, AB, O
(b) A, B, C, O
(c) B, C, O
(d) None of the above
Answer:
(a) A, B, AB, O

Question 13.
Khorana got Nobel prize for
(a) Discovery of RNA
(b) Discovery of DNA
(c) Chemical synthesis of gene
(d) None ‘
Answer:
(c) Chemical synthesis of gene

Question 14.
Secondary pollutant is
(a) CO
(b) C02
(c) PAN
(d) None of these
Answer:
(c) PAN

Question 15.
Chipko movement is launched for protection of
(a) Grass land
(b) Forest
(c) Animal Community
(d) All of the above
Answer:
(b) Forest

Question 16.
TTxttis
(a) Test cross
(b) Back cross
(c) Hybridization
(d) None of the above
Answer:
(a) Test cross

Question 17.
How many types of DNA polymerases are associated with eukaryotic cell ?
(a) 2
(b) 3
(c) 4
(d) 5
Answer:
(d) 5

Question 18.
Example of In Situ conservation is
(a) Zoological garden
(b) Botanical garden
(c) Biological safari park
(d) All of the above
Answer:
(d) All of the above

Question 19.
Which of the following is diploid ?
(a) Male gamete
(b) Ovum
(c) Zygote
(d) All of the above
Answer:
(c) Zygote

Question 20.
Pattern of any population depends on
(a) Density
(b) Distribution
(c) Specific structure
(d) All of the above
Answer:
(d) All of the above

Question 21.
Montreal Protocol is related to control the deleterious effect of
(a) Acid rain
(b) Ozone depletion
(c) Deforestation
(d) Global warming
Answer:
(b) Ozone depletion

Question 22.
Fertilization takes place in
(a) Ovary
(b) Uterus
(c) Fallopian tube
(d) All of the above
Answer:
(c) Fallopian tube

Question 23.
Hugo de-Vries worked on which plant ?
(a) Pea
(b) Evening Primrose
(c) Both
(d) None
Answer:
(b) Evening Primrose

Question 24.
Salmonella is associated with
(a) Polio
(b) T.B,
(c) Typhoid
(d) All of the above
Answer:
(c) Typhoid

Question 25.
AIDS is identified first of all in
(a) USA
(b) France
(c) Russia
(d) All of the above
Answer:
(a) USA

Question 26.
Bones of fore limbs of Bat, and humans are
(a) Homologous
(b) Analogous
(c) Both
(d) None
Answer:
(a) Homologous

Question 27.
Which enzyme is used to join cut ends of DNA?
(a) Ligase
(b) Cellulose
(c) Pectinase
(d) None of the above
Answer:
(a) Ligase

Question 28.
Which of the following serve as biofertilizer in paddy fields?
(a) Yeast
(b) Bacteria
(c) Cyano bacteria
(d) Fungi
Answer:
(c) Cyano bacteria

Question 29.
Which of the following is used in preparing Cheese?
(a) Viruses
(b) Algae
(c) Fungi
(d) Micorobes
Answer:
(d) Micorobes

Question 30.
Statins used for lowering blood cholesterol level
are extracted from
(a) Yeast
(b) Algae
(c) Virus
(d) All of the above
Answer:
(a) Yeast

Question 31.
Microbes are found in
(a) air
(b) water
(c) soil
(d) All of the above
Answer:
(d) All of the above

Question 32.
Ranikhet disease is connected with
(a) Pigs
(b) Cow
(c) Fish
(d) Hens
Answer:
(d) Hens

Question 33.
Induced breeding is done in case of
(a) Apiculture
(b) Pisci culture
(c) Lac culture
(d) Sericulture
Answer:
(b) Pisci culture

Question 34.
Taichung Native-1 is a variety of
(a) Rice
(b) Wheat
(c) Maize
(d) None
Answer:
(a) Rice

Question 35.
Zeba cattle is
(a) Goat
(b) Cat
(c) Cow
(d) Sheep
Answer:
(c) Cow

Non-Objective Type Questions

Short Answer Type Questions

In this section, there are 18 short answer type question (each carryies 2 marks) out of which answers any ten (10) questions. (10 x 2 = 20)

Question 1.
What is co-dominance? Explain with example.
Answer:
In co-dominance both dominant alleles of a gene express themselves equally in F, hybrids. The phenotype ratio matches with genotypic ratio i.e, 1: 2: 1 in F2 generation of offspring. Example of co-dominance can be seen in goat colour in

Question 2.
What is significance of double fertilization?
Answer:
Significance of double fertilization:
(i) Double fertilization is very important in angiospermic plants. If only syngamy occurs in plants and triple fusion does not occur, only 3 zygote will be formed. Endosperm will not be formed and this will result seed with undeveloped embryo or seed without embryo.

(ii) Endosperm is formed due to double fertilization. This provides nutrition to embryo and it contains maternal and paternal chromosomes. A body shows physiological aggressiveness due to hybrid vigour in inner endospermic cells.

Question 3.
What is radio-active pollution? What are the sources of radio-active pollution?
Answer:
Radio-active Pollution: Certain elements such as Radium, Thorium, Uranium emit protons (Alpha particles), electrons (Beta particles) and Gamma particles by disintegration of atomic nuclei. This phenomenon is called radio-activity and these elements are known as radio-active. When the radio-active radiations contaminate to water, air, soil and food materials it is called radio-active pollution.

Question 4.
Define Commensalism and Parasitism.
Answer:
Commensalism: An interaction between two species in which one is benefitted and the other one is neither harmed nor benefitted.
e.g. Orchids growing on trunk/branch of a tree.

Parasitism: An interaction between two species where parasite not only obtains food from its host but also completes its life cycle on the host. e.g. Bacteria, Fungi etc.

Question 5.
What are the ways for controlling amoebiosis?
Answer:
Amoebiosis is caused by a protozoan parasite Entamoeba histolytica, in which pain in stomach and stool with mucus and blood are seen as specific symptom.
Following are the control major of amoebiosis:

1. Patient should take rest and after some interval electrolytic fluid must be taken.
2. For control of disease, emetin, vioform, chinoform and diodoquin should be taken as drug and antibiotics like Terramycine, Erythromycine, Metronidazole and Aureomycin may be helpful in treatment and control of this disease.

Question 6.
What is Jumping Gene (Transposons)?
Answer:
These are capable of changing their locations from one place to another, so it is called jumping genes. It is a mobile fragment of DNA that can change position in a genome, a cause of sequence insertions and deletions in some organisms.

Question 7.
Name four living fossils.
Answer:
A living fossil is a living animal of ancient origin with many primitive characters. A living fossil has been living as such from the time of origin without many changes.
Examples are:

• Peripatus of phylum Arthropoda.
• Limulus of phylum Arthropoda.
• Latimeria-a bony fish.
• Sphenodon-a reptile.

Question 8.
Write any four benefits of micro-propagation.
Answer:
Benefits of micro-propagation:

• By such method crop production increases.
• By such method storage of germplasm can be taken place.
• By Meristem tip culture method disease resistant plants are produced.
• Micropropagation is also beneficial in conservation of biodiversity.

Question 9.
What is fishery? Name few common freshwater and marine edible fishes.
Answer:
Fishery: It is an industry concerned with catching, processing or selling of fish, shell fish or other aquatic animals.
Freshwater edible fishes:

• Catla
• Rohu
• Cirrhina mrigala.

Marine water edible fishes: (a) Hilsa (b) Sardines (c) Mackerel (d) Pomfrets.

Question 10.
Write short notes on gene cloning.
Answer:
The production of living structures genetically identical to their parent structure is known as gene cloning. It is therefore an exact copy of a single living parent. Gene cloning is the act of making copies of single gene. Once a gene is identified clones can be used.

Question 11.
Why is the Human Genome Project called a megaproject?
Answer:
Human Genome Project is called a mega project because it is aimed to sequence every base in human genome. It has developed the ways of mapping the human genome at increasing fine level of precision and to store this information in database and develops tools for data analysis. The magnitude and the requirements for this project are more for opening up new areas and avenues.

Question 12.
What are the functions of t-RNA in the protein synthesis?
Answer:

1. It carries specific amino acids from the cytoplasm to the ribosomal sites for the formation of polypeptide chain according with the sequence specified by m-RNA.
2. The t-RNA charged with the amino acid serves as a adaptor molecule to decode the information on the m- RNA.
3. It comes to elongate the polypeptide chain by the addition of several newly synthesised amino acids.

Question 13.
Define homologous orgAnswer: Give examples.
Answer:
These are the organs of similar structure and origin but dissimilar in functions and form.This is due to common ancestary.
Examples:
(i) The forelimbs of a frog, the wings of a bird, legs of a horse, the hands of a man and the flipper of a whale are homologous organs because all of them have similar pattern of basic plan (pentadacty) i.e. same number of bones, muscles, nerves and blood vessels etc. but they do the different functions such as hopping (frog), flying (bird), running (horse), graping (man) and swimming (whale).

(ii) Phylloclade of Opuntia and Cladode of Ruscus are homologous organs as both are modified stems. Similarly, a thorn of Bougainvillea and a tendril of Cucurbita are homologous as both arise in axillary position.

Question 14.
What is green revolution? List two factors that have led green revolution in India.
Answer: Green revolution is the enormous increase in the food production due to intensive cultivation by use of improved varieties of seeds and fertilizers.
The factors that contributed to the green revolution in India are:

• The development and introduction of high yielding varieties of crop and extension of the high yielding varieties over large area in the country.
• Transfer of technology of scientific farming from research farm to village farmers.

Question 15.
What do you understand by restriction enzyme?
Answer:
Restriction enzymes: These enzymes are nucleases which cut DNA into short pieces containing identifiable genes at specific sites. These pieces are then introduced into plastids, yeasts or plant cells.
Ex. ECORI, Hind-III.

Question 16.
Write short notes on plasmids.
Answer:
A plasmid is small circular double stranded DNA molecule that is distinct from a cell, chromosomal DNA.
Plasmids naturally exist in bacterial cells and they also occur in some eukaryotes. Often, the genes carried in plasmid provide bacteria with genetic advantage, such as antibiotic resistance.

Question 17.
Write short notes on organic evolution.
Answer:
The process by which changes in the genetic composition of populations of organism occur in response to environmental changes is known as organic evolution. Examples of organic evolution include organs that are different in structure but perform similar function. A Dolphin’s flipper’ and human arms are example of organic evolution.

Question 18.
Discuss the concept of IPM.
Answer:
Integrated Pest Management (IPM) aims at minimum use of pesticides to prevent agro-chemical pollution and to adopt natural methods of pest control as far as possible. The natural methods of pest control are the part of a larger agricultural strategy and these include:

1. Use of resistant varieties of crop to local pests.
2. To carry the practice of crop rotation and improved sanitation method.
3. To adopt biological control method and starvation method.
4. To grow planting or a preferred target crop to lure away insects.
5. Use of sterilization strategy, mechanical control, repellents, chemical attractants and natural insecticides etc.

Long Answer Type Questions

There are 6 long answers type question (each carrying 05 marks) out of which answers any three questions. (5 x 3 = 15)

Question 19.
Discuss the characters chosen by Mendel in garden pea. Mention the advantages of selecting this plant for experiment.
Answer:
Gregor Mendel, conducted hybridisation experiments on garden peas for seven years (1856-1863) and proposed the laws of inheritance. During Mendel’s investigations into inheritance patterns it was for the first time that statistical analysis and mathematical logic were applied to problems in biology. His experiments had a large sampling size, which have greater credibility to the data

that he collected. Also, the confirmation of his inferences from experiments on successive generations of his test plants, proved that his results pointed to general rules of inheritance rather than being unsubstantiated ideas. Mendel selected only pea plants for his experiment due to presence of many types of contrasting characters like:

• Round and wrinkled seeds
• Yellow and green seeds
• Violet and white flowers
• Inflated and constricted pods
• Green and yellow pods
• Axillary and terminal flowers
• Tall and dwarf plants

Mendel investigated characters in the garden pea plants that were manifested as two opposite traits which allowed him to set up a basic frame work of rules governing inheritance. Mendel conducted such artificial pollination/ cross pollination experiments using several true breeding pea lines.

Advantages of selecting pea plants for experiment by Mendel:

1. Due to short height of pea plants, it was easy to do experiment on that.
2. Pea plants had a short life cycle so that results could be had within a year.
3. Pea plants produced many seeds in one generation which helped in drawing correct conclusions.
4. Artificial cross-pollination could be easily achieved because androecium and gynoecium were completely enclosed.
5. Pea plants having each of the seven characters he selected were readily available.
6. Mendel took only one character at one time for his experiment.
7. Pea plants are self pollinated and pure.

Question 20.
Give an accout of Neo-Darwinism/Modern concept of evolution.
Answer:
Neo-Darwinism is the improvement of Darwin’s orginal theory of Natural Selection in order to remove its defects.
Important mechanisms for Neo-Darwinism are:
(a) Variations (b) Natural selection (c) Isolation

(a) Variations: Variations which influence evolution are the ones that develop in the genetic machinery of the germ cells. They are formed due to Mutations, Recombinations, Migrations, Hybridisation and Genetic Drift.

(b) Natural Selection: It operates through differential reproduction. Individuals with advantageous variations survives, reach maturity and leave there genes in the gene pool through differential reproduction. Repeated reproductive selection of individuals with specific traits increases the frequency of their genes in the gene pool. Individuals with harmful neutral variations are eliminated at various stages.

(c) Isolation: It is the separation of a segment of population from the rest due to apearance of a barrier. Gene pool of the isolated population changes due to genetic drift and accumulation of different types of reproduction.

Question 21.
Give a labelled diagram of the electron microscopic view of a human sperm and describe it briefly.
Answer:
The human sperm is a microscopic, long, flagellated and haploid motile cell and is formed of head, neck, middle piece and tail.

(i) Head: It constitutes the anterior region of sperm containing nucleus and acrosome. The nucleus is a narrow, flat and oval structure consisting of densely packed nuclear chromatin material. The latter is formed of DNA and nucleo protein. A small pointed sheathy acrosome is found at the anterior region of head and is derived from the golgi bodies. It contains hydrolytic enzyme-hyalourinidase which helps the sperm to penetrate into ovum during fertilization by dispersing the cells of corona radiata.

(ii) Neck: It is very short or indistinguishable region lying in between head and middle piece. It contains the proximal and distal centriole with 9 + 0 arrangement of micro-tubules. The proximal centriole forms the spindle in the first cleavage divison of the fertilised ovum. The distal centriole gives rise to many fine micro-tubules which run upto sperm tail by passing through middle piece.

(iii) Middle piece: It is a cylindrical region lying behind the neck. It contains number of mitochondrial spiral (nebenkern) which encircles the axial fdament arising from distal centriole. The mitochondrial spiral contains the oxidative enzymes which provide energy for movement of sperm by the process called oxidative phosphorylations.

(iv) Tail: It is the longest part of the sperm and is formed of main central axial filament and the outer protoplasmic sheath with small amount of cytoplasm. At the posterior end of tail, the axial filament is naked without any sheath and is called as end piece. The tail undulates rapidly and provides mobility to the sperm with the head forward in the fluid medium.

Question 22.
What is deforestation? Write its causes and effects.
Answer:
Deforestation is the conversion of forest areas to non-forest ones. It is a serious threat to the quality of life, national economy and future of environment. According to an estimate, almost 40>percent forests have been lost in the tropics, compared to only one percent in the temperate region. The present-scenario of deforestation is particularly grim in India.

The main cause of decrease in forest cover in India is deforestation due to expansion of agriculture, urbanization, industrialization, excessive commercial use of timber, fuel, wood etc. The causes of deforestation are population explosion, fires, pests, grazing and gnawing mammals, weather, jhum cultivation, etc.

Effects of deforestation are as follows:

1. Soil erosion has increased;
2. Flood and droughts have become more frequent;
3. Pattern of rain fall is changing;
4. Land slides and avalanches are on the increase;
5. Climate has become warmer;
6. Forest dwilling species are becoming extinct;
7. Consumption of CO₂ and production of O₂ are getting adversely affected.

Question 23.
Give an account of Apiculture.
Answer:
The maintenance of hives of honey bees for the production of honey is called bee keeping or apiculture.
Bee keeping is a small scale industry for the production of honey which have following economic importance:

• Bee keeping gives honey which is an important nutritive substance.
• Bee-hives gives bee-wax which is utilized in making polishes.
• Bee keeping helps in pollination of various crops useful for mankind

Question 24.
Write short notes on Homology and Analogy organ, vestigial organ, Atavism and Connecting links.
Answer:
(i) Homology and Analogy: The organs of similar structure and origin but dissimilar in functions and forms are called as homologous organs and this phenomenon is called homology. The presence of homologous organs implies a common evolutionary origin of amphibians, reptiles, birds and mammals from some ancient fish ancestor. The homologous structures seen in successive generations indicate actual relationship and the possessors are the diverse descendants of common ancestry (Divergent evolution).

The organs that perform the same function but differ in their origin and structure, are called as analogous organs and the phenomenon is called analogy. The wings of an insect are analogous to those of birds and bats because they perform the same function but have dissimilar structure and origin. The wings of an insect are modified outgrowth of the body wall whereas wings of birds and bats are forelimbs.

These organs have arisen in evolutionary process through adaptation of quite different organisms to a similar mode of life (Convergent evolution). On the same line, the similarities in proteins are genes performing a given function among diverse organisms give clues to common ancestry. These biochemical similarities point to the same shared ancestry as structural similiarities among diverse organisms.

(ii) Vestigial organs: These are the reduced and functionless organs which are of no use to the possessor but they still persists generation after generation in reduced form in an individual. They were complete and functional in the ancestors e.g. appendix in man is considered as the remnant of large intestine (caecum) but it is considered to be storage organ for cellulose digestion in herbivorous mammals. The vestigial organs which used to perform a normal function in the ancestor but during the course of evolution, they have been reduced to vestiges.

(iii) Atavism: It is reappearance of ancestral characters other than parents in the newly born offspring, which have either completely disappeared or reduced. The reappearance of short tail in some babies, multiple mammals in some individuals and dense hairy body etc. are the examples of atavism. The reappearance of such ancestral characters favour evolution.

(iv) Connecting links: The organisms which possess the characters of two different groups of organisms are known as connecting links e.g., duckbilled platypus and spiny ant-eater serve as a connecting link between the mammals and reptiles. Similarly lung fishes (Protopterus) is a connecting link between fishes and amphibians.

Bihar Board 12th Chemistry Objective Questions and Answers

Bihar Board 12th Chemistry Objective Answers Chapter 1 The Solid State

Question 1.
Which among the following will show anisotropy ?
(a) Glass
(b) NaBr
(c) Plastic
(d) Rubber
Answer:
(b) NaBr

Question 2.
Which of the following forms a molecular solid when solidified ?
(a) Calcium fluoride
(b) Silicon dioxide
(c) Carbon dioxide
(d) Sodium chloride
Answer:
(c) Carbon dioxide

Question 3.
The major binding force in diamond, silicon and quartz is ……………
(a) electrostatic force
(b) electrical attraction
(c) covalent bond force
(d) van der Waals force
Answer:
(c) covalent bond force

Question 4.
Solid X is a very hard solid which is electrical insulator in solid as well as in molten state and has extremely high melting point. What type of solid is it ?
(a) Ionic solid
(b) Covalent solid
(c) Metallic solid
(d) Molecular solid
Answer:
(b) Covalent solid

Question 5.
Examples of few solids are given below. Find out the example which is not correctly matched.
(a) Ionic solids – NaCl, ZnS
(b) Covalent solids – H₂,l₂
(c) Molecular solids – H₂O_(s)
(d) Metallic solids – Cu, Sn
Answer:
(b) Covalent solids – H₂,l₂

Question 6.
Which of the following solids is the structure of CsCl crystal ?
(a) Body centred cubic
(b) Simple cubic
(c) Face centred cubic
(d) Edge centred cubic
Answer:
(a) Body centred cubic

Question 7.
Which of the following does not represent a type of crystal system ?
(a) Triclinic
(b) Monoclinic
(c) Rhombohedral
(d) Isotropical
Answer:
(d) Isotropical

Question 8.
Which of the following primitive cells show the given parameters ?
a # b # c, α = β = Y = 90°
(a) Cubic
(b) Tetragonal
(c) Orthorhombic
(d) Hexagonal
Answer:
(c) Orthorhombic

Question 9.
Which type of crystals contains more than one Bravais lattice ?
(a) Hexagonal
(b) Triclinic
(c) Rhombohedral
(d) Monoclinic
Answer:
(d) Monoclinic

Question 10.
For the structure given below the site marked as S is a ……………
(a) tetrahedral void
(b) cubic void
(c) octahedral void
(d) none of these

Answer:
(c) octahedral void

Question 11.
A metal crystallises into a lattice containing a sequence of layers as AB AB AB………………….. What percentage of voids are left in the lattice ?
(a) 72%
(b) 48%
(c) 26%
(d) 32%
Answer:
(c) 26%

Question 12.
In ccp arrangement the pattern of successive layers can be designated as …………
(a) AB AB AB
(b) ABC ABC ABC
(c) AB ABC AB
(d)  ABA ABA ABA
Answer:
(b) ABC ABC ABC

Question 13.
The coordination number of metal crystallising in a hexagonal close packing is ………
(a) 12
(b) 4
(c) 8
(d) 6
Answer:
(a) 12

Question 14.
A crystalline structure has radius ratio (r, / r) in the range of 0.225 – 0.414. The coordination number and arrangement of anions around the cations are ………..
(a) 3, plane triangular
(b) 6, octahedral
(c) 4, tetrahedral
(d) 8, cubic
Answer:
(c) 4, tetrahedral

Question 15.
A crystal lattice with alternative +ve and -ve ions has radius ratio 0.524. The coordination number of lattice is …………
(a) 4
(b) 6
(c) 8
(d) 12
Answer:
(b) 6

Question 16.
A solid AB has a rock salt structure. If radius of cation A⁺ is 120 pm, what is the minimum value of radius of B⁺anion (a) 120 pm
(b) 240 pm
(c) 290 pm
(d) 360 pm
Answer:
(c) 290 pm

Question 17.
How many chloride ions are surrounding sodium ion in sodium chloride crystal ?
(a) 4
(b) 8
(c) 6
(d) 12
Answer:
(c) 6

Question 18.
In NaCl structure, ……………
(a) all octahedral and tetrahedral sites are occupied
(b) only octahedral sites are occupied
(c) only tetrahedral sites are occupied
(d) neither octahedral nor tetrahedral sites are occupied.
Answer:
(b) only octahedral sites are occupied

Question 19.
NaCl type crystal (with coordination no. 6 : 6) can be converted into CsCl type crystal (with coordination no. 8 : 8) by applying ……
(a) high temperature
(b) high pressure
(c) high temperature and high pressure
(d) low temperature and low pressure.
Answer:
(b) high pressure

Question 20.
Coordination numbers of Cs⁺ and Cl^– in CsCl crystal are ………….
(a) 8, 8
(b) 4,4
(c) 6,6
(d) 8,4
Answer:
(a) 8, 8

Question 21.
A unit cell of BaCl₂ (fluorite structure) is made up of ………..
(a) four Ba²⁺ ions and four Cl^– ions
(b) four Ba²⁺ ions and eight Cl^– ions
(c) eight Ba²⁺ ions and four Cl^– ions
(d) four Ba²⁺ ions and six Cl^–
Answer:
(c) eight Ba²⁺ ions and four Cl^– ions

Question 22.
In face centred cubic unit cell, edge length is …………..
(a) \(\frac{4}{\sqrt{3}} \mathrm{r}\)
(b) \(\frac{4}{\sqrt{2}} \mathrm{r}\)
(c) 2r
(d) \(\frac{\sqrt{3}}{2} \mathrm{r}\)
Answer:
(b) \(\frac{4}{\sqrt{2}} \mathrm{r}\)

Question 23.
The edge length of fee cell is 508 pm. If radius of cation is 110 pm, the radius of anion is …………
(a) 110 pm
(b) 220 pm
(c) 285 pm
(d) 144 pm
Answer:
(d) 144 pm

Question 24.
The edge length of sodium chloride unit cell is 564 pm. If the size of Cl^– ion is 181 pm. The size of Na⁺ ion will be …….
(a) 101 pm
(b) 181 pm
(c) 410 pm
(d) 202 pm
Answer:
(a) 101 pm

Question 25.
The radii of Na⁺ and Cl^– ions are 95 pm and 181 pm respectively. The edge length of NaCl unit cell is ………..
(a) 276 pm
(b) 138 pm
(c) 552 pm
(d) 415 pm
Answer:
(c) 552 pm

Question 26.
Copper crystallises in fee with a unit cell length of 361 pm. What is the radius of copper atom ?
(a) 157 pm
(b) 181 pm
(c) 127 pm
(d) 108 pm
Answer:
(c) 127 pm

Question 27.
Total volume of atoms present in a fee unit cell of a metal with radius r is …………
(a) \(\frac{12}{3} \pi r^{2}\)
(b) \(\frac{16}{3} \pi r^{3}\)
(c) \(\frac{20}{3} \pi r^{3}\)
(d) \(\frac{24}{3} \pi r^{3}\)
Answer:
(b) \(\frac{16}{3} \pi r^{3}\)

Question 28.
Relationship between atomic radius and the edge length a of a body-centred cubic unit cell is ……..
(a) r = a/2
(b) \(r=\sqrt{a / 2}\)
(c) \(r=\frac{\sqrt{3}}{4} a\)
(d) \(r=\frac{3 a}{2}\)
Answer:
(c) \(r=\frac{\sqrt{3}}{4} a\)

Question 29.
Edge length of a unit cell of chromium metal is 287 pm with bcc arrangement. The atomic radius is of the order
(a) 124.27 pm
(b) 287 pm
(c) 574 pm
(d) 143.5 pm
Answer:
(a) 124.27 pm

Question 30.
The fraction of the total volume occupied by the atoms present in a simple cube is ………….
(a) \(\frac{\pi}{4}\)
(b) \(\frac{\pi}{6}\)
(c) \(\frac{\pi}{3 \sqrt{2}}\)
(d) \(\frac{\pi}{4 \sqrt{2}}\)
Answer:
(b) \(\frac{\pi}{6}\)

Question 31.
A unit cell of sodium chloride has four formula units. The edge length of the unit cell is 0.564 nm. What is the density of sodium chloride ?
(a) 3.89 g cm^-3
(b) 2.16 gem^-3
(c) 3 g cm^-3
(d) 1.82 g cm^-3
Answer:
(b) 2.16 gem^-3

Question 32.
The distance between Na⁺ & Cl^– ions in NaCl with a density 3.165 g cm^-3 is …………..
(a) 497 pm
(b) 248.5 pm
(c) 234 pm
(d) 538.5 pm
Answer:
(b) 248.5 pm

Question 33.
How many lithium atoms are present in a unit cell with edge length 3.5A and density 0.53 g cm^-3 ?
(a) 2
(b) 1
(c) 4
(d) 6
Answer:
(a) 2

Question 34.
Alkali halides do not show Frenkel defect because …………….
(a) cations and anions have almost equal size
(b) there is a large difference in size of cations and anions
(c) cations and anions have low coordination number
(d) anions cannot be accommodated in voids.
Answer:
(a) cations and anions have almost equal size

Question 35.
Which of the following crystals does not exhibit Frenkel defect ?
(a) AgBr
(b) AgCl
(c) KBr
(d) ZnS
Answer:
(c) KBr

Question 36.
What type of stoichiometric defect is shown by ZnS ?
(a) Schottky defect
(b) Frenkel defect
(c) Both Frenkel and Schottky defects
(d) Non-stoichiometric defect
Answer:
(b) Frenkel defect

Question 37.
In a Schottky defect, …………..
(a) an ion moves to interstitial position between the lattice points
(b) electrons are trapped in a lattice site
(c) some lattice sites are vacant
(d) some extra cations are present in interstitial spaces.
Answer:
(c) some lattice sites are vacant

Question 38.
Silver halides generally show ………….
(a) Schottky defect
(b) Frenkel defect
(c) both Frenkel and Schottky defects
(d) cation excess defect.
Answer:
(c) both Frenkel and Schottky defects

Question 39.
An electron trapped in an anion site in a crystal is called ………….
(a) F-centre
(b) Frenkel defect
(c) Schottky defect
(d) interstitial defect
Answer:
(a) F-centre

Question 40.
Which of the following will have metal deficiency defect ?
(a) NaCl
(b) FeO
(c) KCl
(d) ZnO
Answer:
(b) FeO

Question 41.
Pure silicon and germanium behave as …………
(a) conductors
(b) semiconductors
(c) insulators
(d) piezoelectric crystals
Answer:
(c) insulators

Question 42.
To get n-type of semiconductor, germanium should be doped with ………….
(a) gallium
(b) arsenic
(c) aluminium
(d) boron
Answer:
(b) arsenic

Question 43.
p-type semiconductors are formed when Si or Ge are doped with …………
(a) group 14 elements
(b) group 15 elements
(c) group 13 elements
(d) group 18 elements.
Answer:
(c) group 13 elements

Question 44.
Paramagnetic substances are magnetised in a magnetic field in the same direction. Paramagnetism is due to the presence of……………….
(a) one or more unpaired electrons
(b) all paired electrons
(c) permanent spin and orbital motion
(d) parallel and anti-parallel spins in equal numbers.
Answer:
(a) one or more unpaired electrons

Question 45.
Fe₃O₄ is ferrimagnetic at room temperature but at 850 K, it becomes
(a) diamagnetic
(b) ferrimagnetic
(c) paramagnetic
(d) anti-ferromagnetic
Answer:
(c) paramagnetic

Question 46.
Which of the following metal oxides is antiferromagnetic in nature ?
(a) MnO₂
(b) TiO₂
(c) NO₂
(d) CrO₂
Answer:
(a) MnO₂

Question 47.
Which of the following conditions favours the existance of a substance in the solid state ?
(a) High temperature
(b) Low temperature
(c) High thermal energy
(d) Weak cohesive forces
Answer:
(b) Low temperature

Question 48.
Which of the following is an amorphous solid ?
(a) Graphite (c)
(b) Quartz glass (SiO₂)
(c) Chrome alum
(d) Silicon carbide (SiC)
Answer:
(b) Quartz glass (SiO₂)

Question 49.
Iodine molecules are held in the crystals lattice by
(a) London forces
(b) dipole-dipole interactions
(c) covalent bonds
(d) coulombic forces
Answer:
(a) London forces

Question 50.
Which of the following is a network solid ?
(a) SO_2(Solid)
(b) I₂
(c) Diamond
(d) H₂O_(Ice)
Answer:
(c) Diamond

Question 51.
Graphite is a good conductor of electricity due to the presence of_______
(a) lone pair of electrons
(b) free valence electrons
(c) cations
(d) anions
Answer:
(b) free valence electrons

Question 52.
Which of the following oxides behaves as conductor or insulator depending upon temperature ?
(a) TiO
(b) SiO₂
(c) TiO₃
(d) MgO
Answer:
(c) TiO₃

Question 53.
Which of the following oxides shows electrical properties like metals ?
(a) SiO₂
(b) MgO
(c) SO_2(s)
(d) CrO₂
Answer:
(d) CrO₂

Question 54.
The lattice site in a pure crystal cannot be occupied by
(a) molecule
(b) ion
(c) electron
(d) atom
Answer:
(c) electron

Question 55.
Graphite cannot be classified as_____________ .
(a) conducting solid
(b) network solid
(c) covalent solid
(d) ionic solid
Answer:
(d) ionic solid

Question 56.
Cations are present in the interstitial sites in___________
(a) Frenkel defect
(b) Schottky defect
(c) vacancy defect
(d) metal deficiency defect
Answer:
(a) Frenkel defect

Question 57.
Which of the following is true about the charge acquired by p-type semiconductors ?
(a) positive
(b) neutral
(c) negative
(d) depends on concentration of p impurity
Answer:
(b) neutral

Question 58.
In which pair most efficient packing is present ?
(a) hep and bcc
(b) hep and ccp
(c) bcc and ccp
(d) bcc and simple cubic cell
Answer:
(c) bcc and ccp

Question 59.
What is the coordination number in a square close packed structure in two dimensions ?
(a) 2
(b) 3
(c) 4
(d) 6
Answer:
(c) 4

Question 60.
Which kind of defects are introduced by doping ?
(a) Dislocation defects
(b) Schottky defects
(c) Frenkel defects
(d) Electronic defects
Answer:
(d) Electronic defects

Question 61.
The edge lengths of the unit cells in terms of the radius of spheres constituting fee, bcc and simple cube unit cell are respectively.
(a) \(2 \sqrt{2} r, \frac{4 r}{\sqrt{3}}, 2 r\)
(b) \(\frac{4 r}{\sqrt{3}}, 2 \sqrt{2} r, 2 r\)
(c) \(2 \mathrm{r}, 2 \sqrt{2} \mathrm{r}, \frac{4 \mathrm{r}}{\sqrt{3}}\)
(d) \(2 \mathrm{r}, \frac{4 \mathrm{r}}{\sqrt{3}}, 2 \sqrt{2} \mathrm{r}\)
Answer:
(a) \(2 \sqrt{2} r, \frac{4 r}{\sqrt{3}}, 2 r\)

Bihar Board 12th Biology Model Papers

Bihar Board 12th Biology Model Question Paper 4 in English Medium

Time : 3 Hours 15 Min
Total Marks : 70

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 indicate full marks.
3. While answering the questions, the candidate should adhere to the word limit as for as practicable.
4. 15 Minutes of extra time has been allotted for the candidates 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 result will be treated as invalid.
7. In Section – B, there are Non-objective type questions. There are 18 Short answer type questions, out of which any 10 questions are to be answered. Each question carries 2 marks. Apart from this, there are 6 long answer type questions, out of which any 3 of them are to be answered. Each question carries 5 marks
8. Use of any electronic device is prohibited.

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.
Mendel worked on
(a) Garden pea
(b) Chick pea
(c) Grass pea
(d) None of these
Answer:
(a) Garden pea

Question 2.
Thymus is present near
(a) Heart
(b) Kidney
(c) Liver
(d) Testis
Answer:
(a) Heart

Question 3.
Which among the following antibodies, the Nascent child Obtains maximum from mother’s milk.
(a) Ig A
(b) Ig M
(c) Ig B
(d) Ig E
Answer:
(a) Ig A

Question 4.
10% law for energy transfer in a food chain is given by
(a) Tansley
(b) Weismann
(c) Lindmann
(d) None of the above
Answer:
(c) Lindmann

Question 5.
Causative agent of Dengue fever is
(a) Virus
(b) Bacteria
(c) Protozoa
(d) All of the above
Answer:
(a) Virus

Question 6.
New plants develop from leaves in
(a) Cycas
(b) Eichhornia
(c) Bryophyllum
(d) None of the above
Answer:
(c) Bryophyllum

Question 7.
Phosphorus is important constituent of
(a) Plasma membrane
(b) Nucleic Acid
(c) Cellular energy transport system
(d) All of the above
Answer:
(d) All of the above

Question 8.
Which of the following disease is spread by Protozoan parasite?
(a) Malaria
(b) Kala-azar
(c) Amoebiasis
(d) All of the above
Answer:
(d) All of the above

Question 9.
Fingcrlings and larvae of
(a) Silkworm
(b) Honey bee
(c) Fish
(d) All of the above
Answer:
(c) Fish

Question 10.
Inducer molecule in lac operon of E. Coli is chemically.
(a) Amino acid
(b) Disaccharides
(c) Protein
(d) All of the above
Answer:
(b) Disaccharides

Question 11.
In a natural Ecosystem decomposition takes place by
(a) Parasitic Algae
(b) Virus
(c) Bacteria and Fungi
(d) All of the above
Answer:
(c) Bacteria and Fungi

Question 12.
PCR technique is routinely used to detect
(a) Cancer
(b) T.B.
(c) HIV
(d) All of the above
Answer:
(c) HIV

Question 13.
Production of fruit without fertilization is known as
(a) Apomixis
(b) Apogamy
(c) Parthenogenesis
(d) None of the above
Answer:
(c) Parthenogenesis

Question 14.
Chiasma formation occurs during
(a) Amitosis
(b) Mitosis
(c) Meiosis
(d) None of the above
Answer:
(c) Meiosis

Question 15.
Acrosome is a part of
(a) Spermatozoa
(b) RNA
(c) DNA
(d) All of the above
Answer:
(a) Spermatozoa

Question 16.
Biogas contains
(a) H₂S
(b) CH₄
(c) CO₂
(d) All of the above
Answer:
(b) CH₄

Question 17.
How many structural genes are present in lac- operon in E. coli?
(a) 4
(b) 2
(c) 3
(d) None of the above
Answer:
(c) 3

Question 18.
Ozone layer is found in
(a) Troposphere
(b) Stratosphere
(c) Mesosphere
(d) Exosphere
Answer:
(b) Stratosphere

Question 19.
Mendel’s Monohybrid ratio is
(a) 1 : 2
(b) 3 : 1
(c) 9 : 3 : 3 : 1
(d) All of the above
Answer:
(b) 3 : 1

Question 20.
Ta jmahal located in Agra is in danger due to which gas?
(a) CO₂
(b) NO₂
(c) SO₂
(d) CFC
Answer:
(c) SO₂

Question 21.
Which is used to see DNA in laboratory?
(a) Aniline
(b) Carmine
(c) Ithidium Bromide
(d) All of the above
Answer:
(c) Ithidium Bromide

Question 22.
Pyramid of energy is always
(a) Upright
(b) Downward
(c) Both
(d) None of the above
Answer:
(a) Upright

Question 23.
An organism with two identical alleles is said to be
(a) Homozygous
(b) Heterozygous
(c) Dominant
(d) Hybrid
Answer:
(a) Homozygous

Question 24.
Bacteriophase kills
(a) Fungi
(b) Parasites
(c) Bacteria
(d) Viruses
Answer:
(c) Bacteria

Question 25.
Which of the following is used in ELISA test?
(a) Endonuclease
(b) Polymerase
(c) Ligase
(d) Peroxydase
Answer:
(d) Peroxydase

Question 26.
Catla fish is found in
(a) Fresh water
(b) Hard water
(c) Both a and b
(d) None of the above
Answer:
(a) Fresh water

Question 27.
Which of the following fixes nitrogen in Symbiotic association?
(a) Chana
(b) Volvox
(c) Rhizobium
(d) None of the above
Answer:
(c) Rhizobium

Question 28.
Which on of the following is active in treatment of sewage?
(a) Fishes
(b) Fish
(c) Bacteria
(d) All of the above
Answer:
(c) Bacteria

Question 29.
Smoking causes
(a) Asthama
(b) Bronchitis
(c) Lung disease
(d) All of the above
Answer:
(d) All of the above

Question 30.
Which of the following study is called Oncology?
(a) Leprosy
(b) Cholera
(c) Cancer
(d) All of the above
Answer:
(c) Cancer

Question 31.
Elephantiasis is called as
(a) Malaria
(b) Filaria
(c) Kala-azar
(d) All of the above
Answer:
(b) Filaria

Question 32.
Which of the following causes Ozone hole?
(a) Ethylene
(b) Acetylene
(c) Chloro-florp carbon
(d) All of the above
Answer:
(c) Chloro-florp carbon

Question 33.
The process of producing immunity in the body is called
(a) Immunity
(b) Immunization
(c) Allergy
(d) All of the above
Answer:
(b) Immunization

Question 34.
Which of the following is the copper releasing IUD
(a) Lippes loop
(b) Progestasert
(c) LNG 20
(d) CUT
Answer:
(d) CUT

Question 35.
Chiasma formation occurs during
(a) Amitosis
(b) Mitosis
(c) Meiosis
(d) None of the above
Answer:
(c) Meiosis

Non-Objective Type Questions

Short Answer Type Questions

In this section, there are 18 short answer type question (each carryies 2 marks) out of which answers any ten (10) questions. (10 x 2 = 20)

Question 1.
What is Bt cotton?
Answer:
Bt cotton-Bt cotton is a type of toxin, which is obtained from Bacillus thuringiensis. It is called Bt in short form. Bt toxin gene has been cloned from the bacteria and expressed in plants to provide resistance from insects without the requirement of insecticide. Bt toxin genes were isolated from Bacillus thuringiensis and incorporated into the several crop plants such as cotton.

Question 2.
What measures should be opted to prevent from contracting sexually transmitted diseases ?
Answer:
For prevention of sexually transmitted diseases following actions should be opted :

• Avoid sex with unknown partner/multiple partners.
• Always use condoms during coitus.
• In case of doubt, should go to a qualified doctor for early detection and get complete treatment if diagnosed with disease.

Question 3.
Write short notes on Golden rice.
Answer:
Golden rice is a genetically modified variety of rice. It contains the transgenes from the daffodil plants and also from some bacteria which are responsible for the synthesis of (3-carotene which is a component of Vitamin A. Deficiency of vitamin A causes blindness. Therefore, P-carotene present in golden variety of rice can be helpful in preventing the child blindness.

Question 4.
Describe the disease transmitted through blood transfusion.
Answer:
AIDS is a blood-transfusion transmitted disease caused by Human Immuno deficiency Virus (HIV) in which the natural immune system of the body is destroyed and body is infected with various pathogens.

Question 5.
What is tumor ?
Answer:
When cancerous cells by their division from a storage of cells, it is called tumor. Tumor are of two types –
1. Benign, 2. Malignant.

• Benign Tumor – They are restricted to a limited portion and do not extend in other parts of the body.
• Malignant – They can easily spread to different parts of the body and their cells are known as Neoplastic cells.

Question 6.
(i) What is noise pollution ? What are its various sources ?
(ii) What are its effects on human beings ?
(iii) Give some methods to control noise pollution.
Answer:
(i) Noise Pollution : It is the unwanted sound which is dumped into the atmosphere and it interferes with human communication, comfort and health.
Sources : Vehicles, musical horns, machines, transistors, radio, drum, beats of religious processions, amplified rock music and disco etc.

Question 7.
Why we say energy flow in the biosphere is unidirectional?
Answer:
The main source of energy of biosphere is ‘Sun’. During photosynthesis solar energy is converted into the chemical energy in the plants. Plants are consumed by herbivores and chemical energy of plants is partially transferred to herbivores animals. Carnivores consume herbivorous animals, their chemical energy of herbivores is transferred to carnivores. That is why, we can say that flow of energy in the biosphere is unidirectional.

Question 8.
Enumerate the major criterias for self-pollination.
Answer:
In which there is transfer of pollen grains from anther to stigma of same flower or another flower of same plants.

• It is found in bisexual plants only.
• It may occur in Cleistogamous flowers.
• There is no need of pollinating agent in it.

Question 9.
Differentiate between DNA and RNA.
Answer:

Question 10.
Describe the post-fertilization changes in a flower.
Answer:
During fertilization, the pollen tube reaches into the ovule through the micropyle. One of the two gametes, one joins with the egg cell resulting in the production of zygote. This is called syngamy and other with the two polar nuclei producing triploid primary endosperm nucleus. This is called as triple fusion. This completes the process of fertilization. After fertilization, the ovule converts into the seed and the whole ovary develops into a complete fruit. The ovary wall forms.

Question 11.
Write principles of Biotechnology.
Answer:
Principles of Biotechnology :
Biotechnology is based on two main techniques
(i) Genetic engineering-It is the science of manipulation of genes. In a strict sense it involves alterations in the chemistry of genetic material, introduction of the same into host and thereby changing the phenotype of host.

(ii) Biochemical engineering processes devoted for the growth of desired microbe or eukaryotic cell in large quantities in a culture medium in aseptic conditions for the manufacture and multiplication of biotechnological products, such as antibiotics, vaccines, enzymes etc.

Question 12.
Differentiate between Innate and Acquired Immunity?
Answer:
Innate immunity is a kind of non-specific protection of the body which persist from the birth whereas acquired immunity is pathogen-specific in which primary and secondary responses occur which depend upon memory of the primary responses.

Question 13.
Name the hormones invovled in regulation of spermatogenesis.
Answer:
The hormones involved in the regulation of spermatogenesis one follicle stimulating hormones (F.S.H.) and Lutenizing stimulating hormones (L.S.H.) which are secreted by pituitory gland under the influence of gondotropin releasing hormones from the hypothalamus.

Question 14.
Describe about Parthenium Weed.
Answer:
Parthenium is a genus of North American shrubs. Parthenium invades disturbed land including roadsides. It infests pastures and form land causing after disastrous loss of yield. As an invader it first appeared as a contaminant in imported wheat. The plant produces Allelopathic chemical that suppress crop and pasture plants and allergens that affect humans and livestock. It also causes pollen allergies. But, it may be used as a remedy of skin inflammation, diarrhoea, dysentery and malaria etc.

Question 15.
What is Tranquilizers? Explain it with examples.
Answer:
Drugs which are used in patients having mental tension & worries are called tranquilizers.
For example :

• Benzodiazepins-Used in case of mental patient and gives mental peace to them.
• Phenothiazines-It stimulate the patient and gives mental peace through eradicating mental worriness.
• Reserpine-It is obtained from Rauvolfia serpentina and very effective in mental tension and worriness.

Question 16.
List few important uses of Human Genome Project.
Answer:
(i) The genetic make up of an organism or an individual lies in the DNA sequence. The knowledge about the effect of DNA variations among individuals can lead to revolutionary new ways to diagnose, treat and prevent thousands of disorders that affect human beings.

(ii) The learning about non-human organisms, DNA sequences can lead to understanding of their natural capabilities that can be applied towards solving challenges in health care, agriculture and energy production etc.

Question 17.
Draw a labelled diagram of human male reproductive system.
Answer:

Question 18.
Describe the structure of biogas plant. Give various steps involved in obtaining biogas.
Answer:
Biogas plants consists of a concrete tank (10-15 feet deep) in which bio-wastes are collected and a slurry of dung is fed. A floating cover is placed over the slurry which keeps on rising as the gas is produced. The biogas plant has an outlet for supply of biogas and another outlet for removing slurry.
Steps :

1. Slurry of animal dung (dung + water) is fed into the digester.
2. In the digester, microbes break down or decompose the complex compounds of the biomass in the slurry.
3. Thd anaerobic microbes do not require oxygen, so the digesters are designed like a sealed chamber.
4. The process takes a few days and gases like methane, CO₂, hydrogen and hydrogen sulphide are produced.

Long Answer Type Questions

There are 6 long answers type question (each carrying 05 marks) out of which answers any three questions. (5 x 3 = 15)

Question 19.
What is pollination? Give an account of the varied means of cross-pollination in plants.
Answer:
Transfer of pollen grains after sheding from the anther to the stigma of the carpel is called pollination.
Pollination in flowering plants occurs by two methods:

• Self Pollination and
• Cross-Pollination.

(1) Self Pollination – Self pollination involves the transfer of pollen grains from the anther of the flower to the stigma of the same flower or another flower of the same plant.

(2) Cross Pollination – Cross pollination involves the transfer of pollen grains from the flower of one plant to the stigma of the flower of another plant.

Varied means of cross pollination in plants are:

(a) Dicliny – Cross-pollination always occurs when the plants are unisexual and dioecious. Ex-Papaya.
(b) Self Sterility – When the stigma of the gynoecium of a flower is not pollinated by pollen grains of the same flower. Ex-Pea, Potato etc.
(c) Dichogamy – When maturity of male and female parts of a bisexual flower occurs in different times. It is of two types : (i) Protogyny (when gynoecium matures first. Ex-Banyan) and (ii) Protandry (when androecium matures first. Ex:-Maize)
(d) Herkogamy – In some flowers physical barrier present between anther and stigma which avoid self-pollination. Ex-Calotropis
(e) Heterostyly – The flowers of some plants have different lengths of stamens and styles so their self-pollination is not possible. Ex-Primula, Oxalis etc.

Question 20.
What is adaptation? Describe the different types of adaptation in plants of deserts.
Answer:
Adaptation is an attribute of the organism to survive and reproduce in its habitat. Many adaptations have evolved over a long evolutionary time and are genetically fixed. It is of two types-temporary and permanent, e.g. Shrinking of pupil due to bright light is temporary adaptation while change of fore-limbs in feathers for fly in birds is permanant adaptation.

Following adaptations are found in plants of deserts

(a) Its roots are long, thick and goes deep in the soil.
(b) Its stems are fleshy and thick for storage of water.
(c) To check loss of water due to vapourisation, stems are generally cuticulised and fill with dense hairs.
(d) Leaves are changed into small scales and spines, which decreases loss of water due to vapourisation. .
(e) Leaves have suitable tissues for storage of water.
(f) Stomata are embedded in stomatal cavity.
Example of Xerophytic plants are-Opuntia, Euphorbia, Argemone, etc.

Question 21.
Describe the properties of genetic code.
Answer:
The properties of genetic code are as follows :
(a) Triplet nature – The genetic code is a triplet code which is arranged in a sequence on m-RNA.
(b) Unambiguous and Specific-One codon codes for only one amino acid, hence it is unambiguous and specific.
(c) Degenerate code – Some amino acids are coded by more than one codon, hence the code is degenerate.
(d) Commaless form – There are no comma and punctuation marks between the coding triplets (Codons).
(e) Universal – The code is nearly universal. For example, from bacteria to human UUU would code for Phenylalanine (Phe).
(f) Nonsense or Terminator Codon – Three of the 64 codons, namely UAA, UAG and UGA, do not specify any amino acids, but signals the end of the message.
(g) Initiation codon – AUG and sometime GUG are the initiator codon. As AUG stands for methionine, polypeptide chain begins with methionine when they are synthesized.

Question 22.
Define Biodiversity. Describe in brief any three important components of Biodiversity.
Answer:
Biodiversity is the variation of life at all levels of biological organization. In other words variability found in different forms of life like plants, animals and microorganisms and in their genes are called as biodiversity. It voluntarily integrates terresterial, aquatic and ecosystem diversity.

There are three basic components of biodiversity :-

• Genetic diversity
• Species diversity
• Ecological diversity.

(d) Genetic diversity-Genetic diversity is related to the variations of genes within species. A single species might show high diversity at the genetic level over its distributional range. For example, genetic variations shown by the medicinal plant Rauwolfia vomitoria growing in different Himalayan ranges might be in terms of the potency and concentration of the active chemical (reserpine) that the plant produces. India has more than 50,000 genetically different strains of rice and 1,000 varieties of mango.

(e) Species diversity-The diversity at the species level is called species diversity. For example, the Westerm Ghats have a greater amphibian species diversity than Eastern Ghats. Similarly, taking example of plants, Brinjal {Solatium melanogena) Potato (Solarium tuberosum) and Tomato (Solatium lycopersicon) belong to the same genus Solatium but they all too differ at the species level.

(f) Ecological diversity-The diversity at the ecosystem level is called ecological diversity. It is related to the different types of ecosystems, e.g., terrestrial (deserts, rain forest, grass land, etc.) and aquatic (rivers, ponds, lakes, sea, etc.) ecosystems.

Ecological diversity is of three types-Alpha (α), Beta (β) and Gamma (γ) diversity.

(i) Alpha diversity – It refers to the diversity of those organism which belongs to same community and habitat.

(ii) Beta diversity – Diversity between different communities of same habitat is called Beta diversity. If there is more heterogeneity in the habitats in a region or more dissimilarity between communities, there will be more Beta diversity.

(iii) Gamma diversity – Diversity at landscape level is called Gamma diversity. It envolves both types of diversity- alpha and beta. It refers to the diversity of the habitats in the whole geographical region.

Question 23.
How microbes are essential for human welfare? Explain it in detail.
Answer:
Microbes are essential for human welfare because they help through various ways in promotion of our health, foods, agro products and reduction of pollution level as well. These are illustrated below

(a) Microbes are essential for production of dairy products like paneer, curd, butter etc. which are processing products of milk. Production is carried out by the microbes such as bacteria. Similarly bread, idli, vinegar are produced by the activity of microbes.

(b) By using Mithanogen bacteria, production of biogas is possible.

(c) Microbes also help us in the treatment of domestic waste water.

(d) In the field of industries, by activity of microbes, we obtain alcoholic drinks of ionous type, organic acids, vitamin B₂, and B₁₂, dextrins, steroid, amino acids, cyclosporin etc. which all enhances our life.

(e) Microbes are used in the field of treatment against infectious diseases.

(f) In the field of agriculture, microbes are used to increase production of agriculture. We uses microbes as pesticides, weedicides which improve our environmental health.

(g) Microbes are also used as ‘single cell protein’ which fulfills our protein requirements.

Question 24.
Give an account of molecular diagnosis.
Answer:
For effective treatment of a disease, early diagnosis and understanding its pathophysiology is very important. Using conventional method of diagnosis (serum and urine analysis), early detection is not possible. Recombinant DNA technology, polymerase chain reaction (PCR) and Enzyme linked Immuno Sorbent Assay (ELISA) are some of the techniques that serves the purpose of early diagnosis.

Very low concentration of pathogen (bacteria, viruses) can be detected in early stage by application of their nucleic acid by PCR. PCR is now routinely used to detect HIV in suspected AIDS patients. It is being used to detect mutations in genes in suspected cancer patients too. It is powerful technique to identify many other genetic disorder.

ELISA is based on the principle of antigen-antibody interaction. Infection by pathogen can be detected by the presence of antigens (proteins, glyco-proteins) or by detecting the antibodies synthesised against the pathogens. Hybridoma technology is also used to produce monoclonal antibody to detect microscopic pathogens.

Bihar Board 12th Economics Model Papers

Bihar Board 12th Economics Model Question Paper 2 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. Youhave to mark, your selected option, on the OMR-Sheet. Each questiion carries 1 (one) mark. [50 x 1 = 50]

Question 1.
The subject matter of economics is being studied under which branches :
(a) Micro Economics
(b) Macro Economics
(c) Above two
(d) None of the above
Answer:
(c) Above two

Question 2.
On the basis of the ownership of the resources, economies are ?
(a) Centrally planned economy
(b) Market economy
(c) Mixed economy
(d) All of above
Answer:
(c) Mixed economy

Question 3.
Which are the central problems of an economy ?
(a) Allocation of resources
(b) Best use of resources
(c) Economic development
(d) All the above
Answer:
(d) All the above

Question 4.
Macro Economics studies :
(a) Full employment
(b) Aggregate price level
(c) Gross National Product
(d) All the above
Answer:
(d) All the above

Question 5.
This is required for a budget set:
(a) Collection of bundles
(b) Prevailing market price
(c) Total income of the consumer
(d) All the above
Answer:
(d) All the above

Question 6.
In diminishing rate of substitution :
(a) more of goods 1
(b) less of goods 2
(c) more of both 1 and 2
(d) (a) and (b) both
Answer:
(c) more of both 1 and 2

Question 7.
Consumer behaviour is studied in :
(a) Micro Economics
(b) Macro Economics
(c) Income theory
(d) None of the above
Answer:
(b) Macro Economics

Question 9.
Indifference curve is :
(a) Concave to the origin
(b) Convex to the origin
(c) Both the above true
(d) Both the above false
Answer:
(c) Both the above true

Question 10.
The slope of the demand curve is :
(a) left to right downward
(b) left to right upward
(c) parallel to x-axis
(d) none of the above
Answer:
(c) parallel to x-axis

Question 11.
Demand function is expressed by which equation ?
(a) Px
(b) Dx = Px
(c) Dx = ∫(Px)
(d) None of the above
Answer:
(d) None of the above

Question 12.
Short run production function is explained by which law ?
(a) By the law of demand
(b) By law of variable proportions
(c) By law of returns to scale
(d) By elasticity of demand
Answer:
(a) By the law of demand

Question 13.
Tick the correct in the following :
(a) TVC = TC – TFC
(b) TC = TVC – TFC
(c) TFC = TVC + TC
(d) TC = TVC × TFC
Answer:
(b) TC = TVC – TFC

Question 14.
MR is expressed as :
(a) \(\frac { ΔTR }{ ΔQ }\)
(b) \(\frac { TR }{ Q }\)
(c) \(\frac { ΔAR }{ Q }\)
(d) None of the above
Answer:
(a) \(\frac { ΔTR }{ ΔQ }\)

Question 15.
In monopoly and monopolistic condition :
(a) AR = MR
(b) AR > MR
(c) AR < MR
(d) None of the above
Answer:
(a) AR = MR

Question 16.
In every market situation which condition is necessary to be fulfilled for a firm’s equilibrium ?
(a) AR = MC
(b) MR = MC
(c) MC curve should cut the MR curve from below
(d) (b) and (c) both
Answer:
(d) (b) and (c) both

Question 17.
Which of the following statement is true ?
(a) There is direct relationship between the price of a commodity and its Supply
(b) Supply curve moves left to right upward
(c) Supply is affected by many factors
(d) All the above
Answer:
(d) All the above

Question 18.
If the price of a commodity rises by 40% but the supply increases by only 15%, supply of such commodity would be :
(a) Excessive elastic
(b) Elastic
(c) Inelastic
(d) completely inelastic
Answer:
(d) completely inelastic

Question 19.
In equilibrium position :
(a) The amount to be sold is equal to the amount to be purchased.
(b) Market supply is equal to market demand
(c) Neither the firm nor the consumer wants to be destabilised
(d) All the above
Answer:
(d) All the above

Question 20.
Every firm uses labour up to the point:
(a) Where labour’s marginal productivity is equal to the wage rate
(b) Where labour’s marginal productivity is less than the wage rate
(c) Where labor r’s marginal productivity is more than the wage rate
(d) None of the above
Answer:
(a) Where labour’s marginal productivity is equal to the wage rate

Question 21.
In which market product differentiation is found ?
(a) Pure competition
(b) Perfect competition
(c) Monopoly
(d) Monopolistic competition
Answer:
(c) Monopoly

Question 22.
Government decides “price ceiling”
(a) On necessary goods
(b) Which is less than the price decided by market ?
(c) To make it affordable to the common man
(d) All of the above
Answer:
(d) All of the above

Question 23.
Price is determined at the point, where :
(a) Demand of the commodity is high
(b) Supply of the commodity is high
(c) Demand of the commodity and supply of the commodity is equal
(d) None of the above
Answer:
(c) Demand of the commodity and supply of the commodity is equal

Question 24.
Market price is found in :
(a) Short period market
(b) Long period market
(c) Very long period market
(d) None of the above
Answer:
(a) Short period market

Question 25.
British economist John Maynard Keynes famous book “The General Theory” was published in which year :
(a) 1926
(b) 1936
(c) 1946
(d)1956
Answer:
(c) 1946

Question 26.
The great Depression came in which year :
(a) 1949
(b)1939
(c) 1929
(d) 19194
Answer:
(a) 1949

Question 27.
Macro economics sees an economy as a combination of which sectors :
(a) Family
(a) Firm
(c) Government and external sector
(d) All of above
Answer:
(d) All of above

Question 28.
GNPMP = ?
(a) GDPMP – Depreciation
(b) GDPMP + net factor income from abroad
(c) Both the above
(d) None of the above
Answer:
(d) None of the above

Question 29.
Which is the correct sequence of money’s development ?
(a) Commodity money, Paper money, Metal money
(b) Commodity money, Metal money, Paper money
(c) Credit money, Metal money, Paper money
(d) None of the above
Answer:
(a) Commodity money, Paper money, Metal money

Question 30.
Reserve Bank of India has presented four measures of money supply, namely M1, M2, M3 and M4, M1 includes :
(a) C = currency held by public
(b) DD = net demand deposit of the bank
(c) OD = other deposits held with the RBI
(d) All of the above
Answer:
(a) C = currency held by public

Question 31.
Which is common man’s bank ?
(a) Commercial Bank
(b) Central Bank
(c) (a) and (b) both
(d) None of the above
Answer:
(c) (a) and (b) both

Question 32.
(a) \(\frac { 1 }{ CRR }\)
(b) Cash × \(\frac { 1 }{ CRR }\)
(c) Cash × CRR
(d) None of these above
Answer:
(c) Cash × CRR

Question 33.
Which of the following is Central Bank’s function ?
(a) Right of issuing notes
(b) Government’s banker
(c) Custodian of Foreign Exchange Reserves
(d) All of the above
Answer:
(d) All of the above

Question 34.
Which currency is issued by Central Bank of the country ?
(a) Money in circulation
(b) Credit money
(c) Coins
(d) All of the above
Answer:
(a) Money in circulation

Question 35.
In an open economy which are the components of Aggregate Demand :
(a) Consumption
(b) Investment
(c) Consumption + government expenditure
(d) Consumption + Investment + Govt, expenditure + net export
Answer:
(d) Consumption + Investment + Govt, expenditure + net export

Question 36.
APC + APS = ?
(a) 0
(b) 1
(c) Infinity
(d) None of the above
Answer:
(c) Infinity

Question 37.
What are the reasons of excess demand ?
(a) Increase in public expenditure
(b) Increase in money supply
(c) Decrease in taxes
(d) All the above
Answer:
(d) All the above

Question 38.
Indian’s financial year is :
(a) 1st April to 31st March
(b) 1st January to 31st March
(c) 1st July to 30th June
(d) None of the above
Answer:
(a) 1st April to 31st March

Question 39.
In direct taxes which one of the following is included ?
(a) Income Tax
(b) Gift Tax
(c) (a) and (b) both
(d) None of the above
Answer:
(c) (a) and (b) both

Question 40.
In India who issues one rupee note;
(a) Reserve Bank of India
(b) Finance Ministry of govt, of India
(c) State Bank of India
(d) None of the above
Answer:
(b) Finance Ministry of govt, of India

Question 41.
Capital Budget includes:
(a) Revenue receipts and revenue expenditure
(b) Capital receipts and capital expenditure
(c) Direct and Indirect taxes
(d) None of the above
Answer:
(b) Capital receipts and capital expenditure

Question 42.
Primary deficit is :
(a) Fiscal Deficit – Interest Payment
(b) Fiscal Deficit + Interest Payment
(c) (a) and (b) both
(d) None of the above
Answer:
(a) Fiscal Deficit – Interest Payment

Question 43.
Budgets are of the following types :
(a) Balanced Budget
(b) Surplus Budget
(c) Deficit Budget
(d) All the above
Answer:
(d) All the above

Question 44.
Exchange rate is of the following types :
(a) Fixed exchange rate
(b) Flexible echange rate
(c) (a) and (b) both
(d) None of the above
Answer:
(c) (a) and (b) both

Question 45.
During Bretton Woods System most countries had:
(a) Fixed Exchange Rate
(b) Pegged Exchange rate
(c) (a) and (b) both
(d) None of the above
Answer:
(c) (a) and (b) both

Question 46.
Fixed exchange rate has following merits :
(a) Promotes Capital movtinem
(b) Prevents capital outflow
(c) Prevents speculation
(d) All the above
Answer:
(d) All the above

Question 47.
Bretton Woods Conference of 1944 established :
(a) International Monetary Fund
(b) World Bank
(c) (a) and (b) both
(d) None of the above
Answer:
(a) International Monetary Fund

Question 48.
Demerits of flexible exchange rate are :.
(a) Instability and uncertainty
(b) Encourages speculation
(c) Discourage international trade and investment
(d) All of the above
Answer:
(d) All of the above

Question 49.
Balance of Trade = ?
(a) Export of visible items – Import of visible item
(b) Export if visible and invisible items – Import of visible and invisible items
(c) Import of visible items – Export of visible items
(d) None of these
Answer:
(b) Export if visible and invisible items – Import of visible and invisible items

Question 50.
Components of Balance of Payments is :
(a) Current Account
(b) Capital Account
(c) (a) and (b) both
(d) None of the above
Answer:
(c) (a) and (b) both

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.
What do you mean by consumer’s equilibrium ? State its assumptions.
Answer:
The state of balance achieved by an end user of products that refers to the amount of goods and services they can purchase given their present level of income and the current level of prices. Consumer equilibrium allows a consumer to obtain the most satisfaction possible from their income.
Assumptions of consumer’s equilibrium :

1. His money income is given and constant
2. There is no change in the habits and tastes of the consumer throughout the analysis.

Question 2.
Write the meaning of perfectly elastic demand and perfectly inelastic demand.
Answer:
Perfectly elastic demand : It means at a higher price, quantity demanded decrease to zero, and perfectly inelastic demand. It means a change in price has no effect on quantity demanded.

Question 3.
State the relation between Marginal Production and Average Production.
Answer:
Marginal production and average production curves initialy increase then decrease due to the law of diminishing marginal returns.

• Marginal productions : It is the change in total production divided by the change in quantity of resources or inputs.
• Average production : It is the total production divided by the quantity of economic resources.

Question 4.
Clarify the concept of opportunity cost.
Answer:
Opportunity cost in the value of the next best alternative in choosing an alternative.
For example suppose to produce one unit of goods x, the producer has to sacrifice production of 2 units of x, the 2x is the opportunity cost producing one unit of x.

Question 5.
Why short run average cost curve is of “U” shaped ? Write briefly.
Answer:
Long run average cost curve is also known as ‘Envelope curve’. Where as LAC is a continuous curve. .The reason behind the ‘U’. Shape the curve is the Law of Returns to scale. According to this law, as plant size increases, the average cost of production decrease due to economies of scale.”

Question 6.
What do you mean by Total Revenue, Average Revenue and Marginal Revenue ?
Answer:

• Total Revenue : The income earned by a seller or producer after selling the output is called the total revenue.
• Average Revenue : Average Revenue refers to the revenue obtained by the seller by selling the per unit commodity. It is obtained by divideding the total revenue by total output.

Marginal Revenue : Marginal revenue is the change in total revenue which results from the sale of one more or one less unit of output.

Question 7.
Write the three characteristics of perfect competitive market.
Answer:
Characteristics of the Market : Main characteristics (or features) of the market are as follows:

1. One Area : The term market in Economics does not refers to any fixed place but indicates that area where buyers and sellers are present and compete with each other.
2. Presence of both Buyers and Sellers : An area is called the market where both buyers and sellers are present. Absence of any one creates hindrance in converting the area into market.
3. One Commodity : In Economics, every commodity has different market, e.g., market of wheat, market of sugar etc.
4. One Price of the Commodity : Market contains one single price of the commodity due to competition between buyers and sellers.

Hence, on the basis of above feature the market can be defined as :
“In economics market signifies the presence of such groups of buyers and sellers of a commodity who freely competer with each other and as a result one price prevails in the market.”

Question 8.
What is the difference between monopoly and monopolistic competition ?
Answer:
Monopoly differs from perfect competition in the following ways :

1. In monopoly, there is a single seller (or firms) of a product whereas under perfect competition there are large number of sellers (or firms).
2. A monopolist produces or sells a product which has no close substitute on the other hand, under perfect competition, the products sold by the various firms are homogeneous or identical. They are perfect substitutes of each other.
3. In case of monopoly, there is no freedom of entry in the industry whereas under perfect competition, there is free entry and exit of firms in the industry.
4. For a monopolist firm, the demand curve of its product slopes downward to the right. On the other hand, a perfect competitive firm faces a perfectly elastic downward curve (i.e., a horizontal straight line).

Question 9.
What is meant by equilibrium price and equilibrium quanity ?
Answer:
“When the supply and demand curves intersect, the market is in equilibrium. This is where the quantity demanded and quality supplied are equal. The corresponding price is the equilibrium price or market clearing price, the quantity is the equilibrium quantity.”

Question 10.
Differentiate between national income and domestic income.
Answer:
Difference between National Income and domestic Income :

• National Income : “It is the sum total of factor incomes earned or generated by normal residents of a country during on accounting year.”
• Domestic Income : “It is the sum total of factor incomes generated by all the production units located with in domestic territory of a country during an accounting year.”.

Difference : The difference between the two is net factor income from abroad which is added to domestic income to get national income.

symbolical : National income = Domestic income + Net factor income from abroad.

Question 11.
What is meant by private income ? What is the difference between private income and personal income ?
Answer:
Private income refers to.that income which accrues to private sector from all sources, both within domestic territory as well as from rest of the world.
Difference between private income and personal income :
Private Income :

1. It includes income of only private sector.
2. It includes both factor income and transfer earnings.
3. Interest on national debt is a part of national income.

Personal Income :

1. It is a receipt concept. It does not include the income of public sector.
2. It includes transfer income of households and individuals.
3. It includes interest on national debts.

Question 12.
Factor income is divided into how many classes ?
Answer:
Factor income is devided into three classes :

1. Rent income
2. Wages income
3. Profit.

Question 13.
What are the precautions related to the calculation of income method ?
Answer:
Following are the precautions related to income method :

1. Income from the sale of second hand goods
2. Transfer payments
3. Sales of shares and bonds
4. Income from Illegal activities
5. Wind full gains
6. Imputed Rent
7. Indirect Takes
8. Corporation Tax and income tax.
9. Deata Duties, Gift tax
10. Travelling Allowances.

Question 14.
What is meant by under employment
equilibrium and over full employment equilibrium ?
Answer:
Underemployment equilibrium : refers to a situation with a persistent shortfall relative to full „ employment and potential output so that unemployment is higher than at the natural rate of unemployment.”

Over full employment equilibrium occurs when a country’s gross domestic product (GDP) is higher than normal.

Question 15.
Write the names of main measures of monetary policy.
Answer:
Following are the measures of monetary i policy of India :

1. Measures of Expansion of currency.
2. Measures of credit control
3. Quantitative credit control
4. Quantitative credit control
5. Statutory liquidity ratio
6. Cash reserve ratio
7. Multiple rate of interest
8. Repo Rate and Reverse repo rate.

Question 16.
Describe the various types of production cost.
Answer:
Following are the types of production cost.
Money cost :
(a) Explicit cost
(b) Implicit cost
(c) Normal profit.

Question 17.
What is an economic activity ?
Answer:
Economic activity is an important component , of subject matter of economics. All economic activities arising out of unlimited wants and scarce means are included in the subject matter of economics.

According to the modern economists, “that activity is called economic activity which is related to the use of limited resources for satisfying human wants.”

Question 18.
What do you understand by Micro economics ?
Answer:
Small units of an economy are included in micro 1 economics e.g. one consumer, one producer, one firm, one industry etc. In other words, individual units are studied in micro economics. According to K.E. Boulding, “Micro economics may be defind as that branch of analysis, which studies the economics behaviour of the individual unit, may be a person, a particular house-hold or a particular firm. It is a study of one particular unit rather than all the units combined together.”

Question 19.
Define capitalist economy.
Answer:
Capitalist economy is a system of economic organisation featured by the private ownership and the use of private profit of man-made and the nature-made capital or in other words, capitalist economy is that economy in which means of production are controlled and regulated by private organisation. Market economy contains the following important features

1. Private property
2. Economic freedom
3. Laissez faire & free trade
4. Competition
5. Price mechanism

Question 20.
Explain the Law of Diminishing Marginal Utility.
Answer:
Law of diminishing marginal utility is a fundamental and universal law. According to this law, as we go on utilizing standard additional units of commodity continuously, marginal utility obtained from use of every additional unit decreases. It occurs or happens in all goods and services. Therefore, this law is called fundamental and universal law of satisfaction.

According to this law, as the stock of goods increases with people, marginal utility obtained from additional units of that commodity decreases after a limit.

Question 21.
Explain the circular flow income.
Answer:
Production gives birth to income, income to consumption, consumption to expenditure and again expenditure to income and production. Thus, circular flow of income earning economic activities takes place in the economy.

According to hipsey, “The circular flow of income is the flow of payment and receipt between domestic firms and domestic households.”

Hence, the circular flow of income refers to flow of money income or the flow of goods and services across different sectors of the economy in a circular form.

Question 22.
Distinguish between national income and domestic income.
Answer:
National income :

1. It is related to the generation of income by public and private sector.
2. It goes not include transfer income.
3. It does not include interest on national debts.
4. It include corporate tax and corporate savings.

Domestic Income :

1. It is a receipt concept. It does not include the income of public sector.
2. It includes transfer income of households and individuals.
3. It includes interest on national debts.
4. It neither includes corporate tax nor corporate savings.

Question 23.
Define commercial bank.
Answer:
Commercial banks perform general banking functions. A commercial bank is an institution which deal with money and credit. It accepts deposits from the public, makes the fund available to those who need them and helps in remittance of money from one place to another.

1. According to Banking Regulation Act, “Banking means the accepting for the purpose of tending and investment of deposits of money from the public, repayable on demand or otherwise, and with draw able by cheque, draft, order or otherwise.”
2. According to Horace white, “Bank is a manufacturer of credit and a machine for facilitating exchanges.”

Question 24.
Explain the subject matter of economics.
Answer:
Subject Matter of Economics : Various economists have presented the subject matter of economics in different ways. On the basis of various economists’ view points, the subject matter of economics can broadly be divided into four categories :

1. Wealth-related Viewpoint: Classical economists Adam Smith, J.B. Say, Walker, Senior etc. have included wealth, its earning, distribution and use in the subject matter of economics. These economists have included economic man and his activities into the subject matter of economics.
2. Welfare-related Viewpoint: Marshall, Pious, Canon established the concept of human-welfare (instead of wealth) in the subject matter of economics. According to welfare-related viewpoint, those economic activities should be included in the subject matter of economics which are associated with physical welfare.
3. Scarcity-related Viewpoint: Robbins has included ‘problem of choice’ related to limited resources and unlimited ends in the subject matter of economics. According to Robbins those human activities are included in subject matter of economics with which human being tries to fulfill his unlimited ends with limited resources.
4. Growth-related Viewpoint : Modern economists like Samuelson has included growth-based activities in the subject matter of economics. According to Samuelson both the aspects i.e. distribution of limited resources’ and ‘economic growth’ are the part of subject matter of economics.

Question 25.
Explain marginal utility.
Answer:
Marginal Utility is the addition to the total utility by consuming an extra unit of a commodity by the consumer. Symbolically:
MU = ATU/An or, MU = TU – TU„
Law of diminishing marginal utility states that consumer consumes more and more of commodity, the marginal utility obtained from an additional unit of it goes on diminishing, other things remaining the same.

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 law of demand with the help of a diagram. Explain any five factors affecting the demand of a commodity.
Answer:
Law of demand states that there is an inverse relation between the price of a commodity and its quantity demanded assuming all other factors effecting demand remain constants. It means that when the price of a goods falls, the demand for the goods rises and when price the demand falls.

There is same price in the market. All consumers purchase commodity according to their needs. The marker demand curve is the total amount demanded by all consumers at different prices. The market demand curve slopes from left down to the right.
Factors affecting the demand of commodity are as below :

1. Price of the commodity itself: When a commodity is selling at very high price, only rich people are able to buy it. So the demand of commodity will be less. But when the price is low more and more people will be able to buy it and the demand of the commodity would be more. Thus, the demand of the commodity is greatly influenced by its price.
2. Price of other related goods : The demand for a commodity is also influenced by prices of other related goods as substitutes.
3. Leves of income of the consumer : consumers demand is also influenced by the size of this income.This is but natural that with increase in the level of income, there is increase in the demand of goods and services.
   (iv) Tastes and preference of consumers : Tastes and preference of the consumers also influence his demand. A taste, fashions, preferences of the consumer keep on changing and is his demand.
4. Population : The change in the population in a country changes the demand.
5. Income distribution: It is only the size or level of income which affects the demand but also the nature of income distributions in the country
6. State of Trade : During a period of boom a period in which there is higher circulation of money and the production level is at a peak, the employment of resources reaches the optimum level. Consequently there is more purchasing power in the hands of the people.

Question 27.
What is meant by returns to scale ? Using a suitable diagram, explain the concepts of increasing constant and diminishing returns to scale.
Answer:
Return to scale : Return to scale refers to long run production when none of the factors of production remains fixed. All factors of production became variable and they can be changed also.
According to watson, “Returns to scale refers to the behaviour of total output as all inputs are varied in the same proportion and is a long-run concept.”
Return of scale is of three types as discussed below :
(i) Increasing Returns to scale : Increasing returns to scale occur when a given percentage increase in all factor inputs causes proportionately greater increase in output. In this way, it factors of production are increased 10%, then production increased more than 10%. Increasing return to scale occur due to division of labour and specilization.

(ii) Constant Returns to scale : Constant return to scale occurs when a given percentage increase in all factors inputs causes equal proportionate increase in output. If factors of production are increased 10% then production also increased by 10% and vice versa.

(iii) Diminishing Return to scale : Diminishing returns to scale occurs when a given percentage increase in factors of productions causes proportionately lesser increase in output.
In diminishing Retur to scale =
Proportionate increase inproduction <
Proportionate increase in factors of production.

Question 28.
What do you mean by double counting problem ? How can it be avoided Explain with an illustration. .
Answer:
Meaning : Double counting means counting of the value of the same product (or expenditure) more than once. How ? According to output method, of calculating national income value of only final goods and services produced by all the production units of a country during a year should be counted. In other words, value of intermediate goods which enter into final goods Ce.g. paper used in printing of books, raw cotton used in garments, wheat used in making breads, should not be taken into account.

But in actual practice, while taking value of final goods, value of intermediate goods also gets included because every producer treats the commodity he sells as final product irrespective of weather it is used as intermediate or final good. For instance, while taking value of final goods like cycles the value of tyres, tubes, frames, bells etc. (intermediate goods) used in manufacturing these cycles also gets included inadvertently.

In this way certain items are counted more than once resulting in over-estimation of national product to the extent of the value of intermediate goods included. This is called the problem of double counting which means counting value of the same commodity more than once.

How to avoid Double Counting : Theoritically we may say that there may be two alternative ways of avoiding double counting namely

1. final product approach
2. value added approach.

But in actual practice, double counting still occurs unintentionally in final product approach because every producer treats the product he sells as final product though the same night have been used by the buyer as an intermediate product.

Therefore, this problem is perfectly solved by value added method according to this method ‘instead of taking value of final products, value added by each firm at each stage of production is included.

Clearly value added by all the four firms is Rs. 3500 comprising Rs. 1000 by A+ Rs 500 by B + Rs. 700 by C + Rs. 1300 by D. There is no scope of double counting in this method. Thus to avoid double counting, the value added method also known as industry of origin method is used in computation of national income. It is worth mentioning that total value added is equal to value of final product.

Question 29.
Define investment multiplier. What is the relationship between investment and marginal propensity to consume.”
Answer:
Difinition of Investment multiplier :
According to Dillard, “Investment multiplier is the ratio of an increase of income to given increase in investment.” Relation between Multiplier and marginal propensity to consume (MPC) : Keynesian investment multiplier depends on marginal propensity to consume (MPC). Higher the marginal propensity to consume, greater will-be the size of multiplier, on the contrary lower the MPC, smaller will be the size of multiplier.
So, there is direct relation between multiplier and MPC
multiplier (k) = \(\frac { 1 }{ 1-MPC }\)
We know that k = \(\frac { ΔY }{ Δ1 }\)
Y=C +I; ΔY = ΔC +ΔI
ΔI = ΔY -ΔC
Here ΔI = change in Investment ΔY = change in Income and ΔC = change in consumptions.
putting the value of AI in equation (i) we have
k = \(\frac { ∆Y }{ ∆I }\)
Dividing right hand side of the equation by ΔY

It is clear that by knowing the value of either MPC or MPS, the value of multiplier can be calculated. Higher the MPC ‘greater will be the value of multiplier. Thus, MPC and multiplier are directly related while MPS and Multiplier are inversely related.

Question 30.
What is excess demand How can it be controlled.
Answer:
(i) Excess Demand : Meaning : If aggregate demand and aggregate supply attain equilibrium at the point beyond full employment, the situation of excess demand appears. In other words, when aggregate demand exceeds aggregate supply at full employment level, excess demand arises.

Thus, “Excess demand refers to a situation in which aggregate demand becomes excess of aggregate supply corresponding to full employment in the economy.” Excess Demand Aggregate Supply corresponding to Full Employment Level

(ii) In situation of excess demand, the aggregate demand exceeds the required demand, hence, increased demand will not put any reaction on employment and production levels because factors are already at full employment level. In this situation of excess demand (in which aggregate demand exceeds aggregate supply) the prices of goods and services rise and situation of inflation arises in the economy.
Characteristics of Excess Demand :

1. When existing aggregate demand exceeds aggregate supply of full employment level, it becomes the situation of excess demand.
2. When aggregate demand exceeds required demand, there is not effect on employment and production level and they remain constant.
3. The difference between aggregate demand and aggregation supply is tremed as ‘Inflationary Gap’ Thus, inflationary gap is measured as the difference, between ‘aggregate demand beyond full employment’ and aggregation demand at full employment’.
   i. e., Inflationary Gap = Aggregate Demand beyond Full Employment – Aggregate Demand at Full Employment.
4. Higher the inflationary gap, more will be the excess demand, i.e., inflationary gap is the measurement of excess demand. Excess Demand : Diagrammatic Representation

(iii) In adjoining fig the situation of excess demand has been shown. Aggregate demand curve AD refers to the situation of full employment. At full employment level Y, required aggregate demand is EY. Aggregate demand beyond full employment is shown by AD] line where aggregate demand becomes FY. Existing aggregate demand FY exceeds required aggregate demand EY and the difference EF becomes excess demand.
Diagrammatically,

Excess Demand = FY – EY – EF
Effects on Excess Demand

(a) Effects on Production : In situation of excess demand, production remains constant, excess demand only puts excess pressure on existing supply.

(b) Effects on Employment: In situation of excess demand, employment remains unaffected because the economy is already at full employment level and hence, there is no possibility of employment increase due to increased demand.

(c) Effects on Prices : The economy being already working at full employment level, no possibility of production increase appears in case of excess demand. Hence, supply falls short of excess demand and as a result, prices of goods and services start rising. In adjoining fig., OL is the production level at full employment level which remains constant even if aggregate demand increases to AD (7 from ∆DF. In this situation of excess demand, only price level rises from OP₁ to OP₂?

Question 31.
Explain the law of demand and what are its assumptions ?
Answer:
Law of demand-Low of demand explains quantitative relation beholden price of goods and quantity demanded. Every consumer has a psychology to buy less amount or quantity of anything of high price and more quantity of low price, ceteris Paribus (other things being equal), there is inverse relationship between price of a goods and when price is low, demand is high.
Thus, p ∞ \(\frac { 1 }{ Q }\) – where,
P = Price of commodity
Q =Quantity demanded

Assumptions of the law of demand-Law of demand is based on few assumptions. These assumptions are-

1. Consumer’s income should remain contant.
2. Consumer’s taste, nature, etc. should remain constant.
3. Consumer remains unknown with new substitutes.
4. There is no possibility of price change in future.

Question 32.
What do you understand by National Income ? Explain any two methods of calculating National Income.
Answer:
Net National product at factor cost (NNPFC) is known as ‘National Income’ NNPFC is the sum total of net domestic product at factor cost and net factor income from abroad.

Net National product at factor cost (NNPFC) or national income is the sum total of factor incomes (rent + interest + profit + wages) generated within the domestic territary of a country, alongwith net factor income from abroad during a year.
NNPFC is the sum total of factor incomes earned by normal residents of a country during year.

(a) First step-identification and classification of productive enterprise.
At the very first step, we are to identify and classify various productive enterprises of an economy. Broadly speaking, we can classify the economy into the following three sectors-

• Primary sector
• Secondary sector
• Tertiary sector

(b) Second step-Calculation of net value of output to estimate the net value added in each identified enterprise in first step the following estimated are calculated

• Value of output
• value of intermediate consumption
• consumption of fixed capital,

i.e., Depreciation.
Value of output is worked out by multiplying the amount of goods and services by each enterprises with their market price. Value of intermediate consumption is calculated by using the prices paid by the enterprise. Consumption of fixed capital is also estimated as per rules and regulations.
[Net value added = Value of output – Intermediate consumption – Net indirect taxes]

(c) Third step-Calculation of net factor income from abroad.
The third and final step in the estimation of national incomes is to estimate the net factor income earned from abroad and add it to the net domestic product at factor cost. This gives us the national income.

Question 33.
What is Barter system ? Mention its difficulties.
Answer:
The direct exchange of goods for goods without the use of money is called barter system. The major drawbacks of the barter system are-

1. Lack of double coincidence of wants-The lack of double coincidence of wants is the major drawback of the barter system. It is very rare when the owner of some goods or services could find someone who wanted his goods or services and possessed that goods or services that the first person wanted. No, exchange is possible if the double coincidence of wants is not there.
2. Lack of common measure of value-The second main drawback of barter system is the absence of a common unit of measurement in which the value of goods and services can be measured. In the absence of common unit, proper accounting is not possible.
3. Lack of standard for deferred payments- The third drawback of the barter system is that it lacks any satisfactory unit to engage in contracts involving future payments. In a barter economy, future payments would have to be stated in specific goods or services which may involve disagreement over the quality of goods even on the commodity used for repayment.
4. Lack of store of value-The bater system does not provide for any method of storing purchasing power for future use. It can be stored only in terms of commodities which subject to storage cost, durability, increases or decreases in the value of goods and the difficulty in disposing of the commodity without loss