Bihar Board 12th Chemistry Objective Answers Chapter 10 Haloalkanes and Haloarenes

Bihar Board 12th Chemistry Objective Questions and Answers

Bihar Board 12th Chemistry Objective Answers Chapter 10 Haloalkanes and Haloarenes

Question 1.
Which of the following is a primary halide ?
(a) iso-Propyl iodide
(b) sec-Butyl iodide
(c) tert-Butyl bromide
(d) neo-Hexyl chloride
Answer:
(a) iso-Propyl iodide

Question 2.
Which of the following is not an allylic halide ?
(a) 4-Bromopent-2-ene
(b) 3-Bromo-2-methylbut-1-ene
(c) 1-Bromobut-2-ene
(d) 4-Bromobut-1-ene
Answer:
(d) 4-Bromobut-1-ene

Question 3.
The IUPAC name of tertiary butyl chloride is
(a) 2-chloro-2-methypropane
(b) 3-chlorobutane
(c) 4-chlorobutane
(d) 1, 2-chloro-3-methylporpane
Answer:
(a) 2-chloro-2-methypropane

Question 4.
The 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 5.
The IUPAC name of the compound is

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

Question 6.
Which of the following compounds can yield only one monochlorinated product upon free radical chlorina­tion ?
(a) 2, 2-Dimethylpropane
(b) 2-Methylpropane
(c) 2-Methylbutance
(d) n-Butane
Answer:
(a) 2, 2-Dimethylpropane

Question 7.
Bromination of methane in presence of sunlight is a
(a) nucleophilic substitution
(b) free radical substitution
(c) electrophilic substitution
(d) nucleophilic addition
Answer:
(b) free radical substitution

Question 8.

Question 9.
The reaction

(a) nucleophilic addition
(b) free radical addition
(c) electrophilic addition
(d) electrophilic substitution
Answer:

Question 10.
Which of the following reactions follows Markovnikov’s rule ?
(a) C₂H₄ + HBr
(b) C₃H₆+Cl₂
(c) C₃H₆+ HBr
(d) C₃H₆ + Br₂
Answer:
(c) C₃H₆+ HBr

Question 11.
Methyl bromide reacts with AgF to give methyl fluride and silver bromide. This reaction is called
(a) Fitting reaction
(b) Swarts reaction
(c) Wurtz reaction
(d) Finkelstein reaction
Answer:
(b) Swarts reaction

Question 12.
Which of the following molecules has highest dipole moment ?
(a) CH₃Cl
(b) CH₂Cl₂
(c) CHCl₂
(d) CCl₄
Answer:
(a) CH₃Cl

Question 13.
Which of the following compounds has the highest boiling point ?
(a) CH₃CH₂CH₂Cl
(b) CH₃CH₂CH₂CH₂Cl
(c) CH₃CH(CH₃)CH₂CH₂Cl
(d) (CH₃)₃CCl
Answer:
(b) CH₃CH₂CH₂CH₂Cl

Question 14.
Which one of the following is not correct order of boiling point of the alkyl/aryl halides ?
(a) CHCl₃ > CH₂Cl₂
(b) CH₃(CH₂)₃CI>CH₃(CH₂)₂Cl
(c) (CH₃)₃CCl > (CH₃)₂CHCH₂Cl
(d) CH₃(CH₂)₃Cl >CH₃CH₂CHClCH₃
Answer:
(c) (CH₃)₃CCl > (CH₃)₂CHCH₂Cl

Question 15.
Which of the following compounds will have highest melthing point ?
(a) Chlorobenzene
(b) o-Dichlorobenzene
(c) m-Dichlorobenzene
(d) p-Dichlorobenzene
Answer:
(d) p-Dichlorobenzene

Question 16.
Choose the correct increasing order of density of the following compound.
(a) C₃H₇CI < C₃H₇I < CH₂CI₂ < CCI₄
(b) C₃H₇I < C₃H₇CI < CH₂CI₂ < CCI₄
(c) C₃H₇I < C₃H₇CI < CCI₄ < CH₂CI₂
(d) CCI₄ < CH₂CI₂ < C₃H₇I < C₃H₇CI
Answer:
(a) C₃H₇CI < C₃H₇I < CH₂CI₂ < CCI₄

Question 17.
Alkyl halides are immiscible in water though they are polar because
(a) they react with water to give alcohols
(b) they cannot form hydrogen bonds with water
(c) C – X bond cannot be broken easily
(d) they are stable compounds and are not reactive
Answer:
(b) they cannot form hydrogen bonds with water

Question 18.
Butane nitrile can be prepared by heating
(a) propyl alcohol with KCN
(b) butyl chloride with KCN
(c) butyl alcohol with KCN
(d) propyl chloride with KCN
Answer:
(b) butyl chloride with KCN

Question 19.
Ethyl alcohol is obtained when ethyl chloride is beild with
(a) alcohoic KOH
(b) aqueous KOH
(c) water
(d) aqueous KMnO₄
Answer:
(b) aqueous KOH

Question 20.
Which of the following alkyl halide undergoes hydrolysis with aqueous KOH at the fastest rate ?
(a) CH₃CH₂CH₂CI
(b) CH₃CH₂CI
(c) CH₃CH₂CH₂CH₂CI
(d) CH₃CH₂CH(Br)CH₃
Answer:
(d) CH₃CH₂CH(Br)CH₃

Question 21.
The alkyl halide is converted into an alcohol by
(a) elimination
(b) dehydrohalogenation
(c) addition
(d) substitution
Answer:
(d) substitution

Question 22.
An alkyl halide, RX reacts with KCN to give propane nitrile, RX is
(a) C₃H₇Br
(b) C₄H₉Br
(c) C₂H₅Br
(d) C₅H₁₁Br
Answer:
(c) C₂H₅Br

Question 23.
Tertiary alkyl halides are practically inert to substitution by S_N2 mechanism because
(a) the carbocation formed is unstable
(b) there is steric hindrance
(c) there is inductive effect
(d) the rate of reaction is faster in S_N2 mechanism
Answer:
(b) there is steric hindrance

Question 24.
Among the choices of alkyl bromide, the least reactive bromide in S_N2 reaction is
(a) 1- bromopentane
(b) 2 – bromo -2- methylbutane
(c) 1 – bromo -3- methylbutane
(d) 1 – bromo -2- methylbutane
Answer:
(b) 2 – bromo -2- methylbutane

Question 25.
Which of the following haloalkanes is most reactive ?
(a) 1-Chloropropane
(b) 1-Bromopropane
(c) 2-Chloropropane
(d) 2-Bromopropane
Answer:
(d) 2-Bromopropane

Question 26.
Consider the following bromides :

The correct order of S_Ni reactivity is
(a) A > B > C
(b) B > C > A
(c) B > A > C
(d) C > B > A
Answer:
(b) B > C > A

Question 27.
Consider the following reaction :

The reaction proceeds with 98% recemisation. The reaction may follow
(a) S_N1 mechanism
(b) S_N2 mechanism
(c) E1 mechanism
(d) E2 mechanism
Answer:
(a) S_N1 mechanism

Question 28.
Which one of the following chlorohydrocarbons readily undergoes solvolysis ?

Answer:
(c)

Question 29.
Which of the following is the most reactive towards nucleophilic substitution reaction ?
(a) ClCH₂ — CH = CH₂
(b) CH₂ = CH — Cl
(c) CH₃CH = CH — Cl
(d) C₆H₅CI
Answer:
(a) ClCH₂ — CH = CH₂

Question 30.
S_N1 reaction is fastest in

Answer:
(c)

Question 31.
Which of the following alkyl halides is hydrolysed by S_N1 mechanism ?
(a) CH₃Cl
(b) CH₃CH₂Cl
(c) CH₃CH₂CH₂Cl
(d) (CH₃)₃CCI
Answer:
(d) (CH₃)₃CCI

Question 32.
Which of the following will give enantiomeric pair on reaction with water due to presence of asymmetric carbon atom ?

Answer:
(c)

Question 33.
Which of the following is most reactive towards aqueous NaOH?
(a) C₆H₅Cl
(b) C₆H₅CH₂Cl
(c) C₆H₅Br
(d) BrC₆H₄Br
Answer:
(b) C₆H₅CH₂Cl

Question 34.
Which of the following haloalkanes reacts with aqueous KOH most easily ?
(a) 1-Bromobutane
(b) 2-Bromobutane
(c) 2-Bromo-2-mthylpropane
(d) 2-Chlorobutane
Answer:
(c) 2-Bromo-2-mthylpropane

Question 35.
Which alkyl halide exhibits complete recemisation in S_N1 reaction ?
(a) (CH₃)₃CCl
(b) CH₃CH₂CH₂Cl
(c) CH₃CH₂Cl
(d) C₆H₅CH₂Cl
Answer:
(d) C₆H₅CH₂Cl

Question 36.
The order of reactivity of various alkyl halides towards nucleophilic substitution follows the order
(a) R – I>R – Br>R – Cl>R – F
(b) R – F>R – Cl>R – Br>R – I
(c) R – Cl>R – Br>R – I>R – F
(d) R – Br>R – I>R- Cl>R – F
Answer:
(a) R – I>R – Br>R – Cl>R – F

Question 37.
2-Bromo-3,3-dimethyIbutance on reaction with aqueous KOH yields X as the major product. X is
(a) 2, 3, 3-trimethylpropan-1-ol
(b) 2, 2-dimethylbutan-3-ol
(c) 2, 3-dimethylbutan-2-ol
(d) 2,2-dimethylpropan-2-ol
Answer:
(c) 2, 3-dimethylbutan-2-ol

Question 38.
Ethylene dichloride and ethylidene chloride are isomeric compounds. The false statement about these isomers is that they ………………..
(a) are both hydrolysed to the same product
(b) contain the same percentage of chlorine
(c) are position isomers
(d) react with alcoholic potash and give the same product
Answer:
(a) are both hydrolysed to the same product

Question 39.
The major product formed in the following reaction is


Answer:
(d)

Question 40.
A mixture of 1-chloropropane and 2-chloropropane when treated with alcoholic KOH gives
(a) prop-1 -ene
(b)  prop-2-ene
(c) a mixture of prop-1-ene and prop-2-ene
(d) propanol
Answer:
(a) prop-1 -ene

Question 41.
2-Chloro-2-methylpropane on reaction with ale. KOH gives X as the product. X is
(a) but-2-ene
(b)  2-methylbut-1-ene
(c) 2-methylprop-1-ene
(d) 2-methylbutaion-2-ol
Answer:
(c) 2-methylprop-1-ene

Question 42.
Reaction of trans-2-phenyl-l-bromocyclopentane on reaction with alcoholic KOH produces
(a) 4-phenylcyclopentene
(b) 2-phenylcylopentene
(c) 1-phenylcyclopenetene
(d) 3-phenylcyclopentene
Answer:
(d) 3-phenylcyclopentene

Question 43.
Identify (Z) in the following reaction series.

Answer:
(b)

Question 44.
The ease of dehydrohalogenation of alkyl halide with alcoholic KOH is
(a)3°<2°< 1°
(b) 3°>2°> 1°
(c) 3°<2°> 1°
(d) 3°>2°< 1°
Answer:
(b) 3°>2°> 1°

Question 45.
Elimination of bromine from 2-bromobutane results in the formation of
(a) equimolar mixture of 1 and 2-butene
(b) predominantly 2-butene
(c) predominantly 1-butene
(d) predominantly 2-butyne
Answer:
(b) predominantly 2-butene

Question 46.

In the given reaction what will be the final product ?
(a) CH₃CH₂CH₂I
(b) CH₃CHICH₂I
(c) CH₃CH₂CH₂CH₂CH₃
(d) CH₃CH₂CHI₂
Answer:
(a) CH₃CH₂CH₂I

Question 47.
The order of reactivites of methyl halides in the formation of Grignard reagent is
(a) CH₃I>CH₃Br>CH₃CI
(b) CH₃CI > CH₃Br > CH₃I
(c) CH₃Br>CH₃CI>CH₃I
(d) CH₃Br > CH₃I > CH ₃CI
Answer:
(a) CH₃I>CH₃Br>CH₃CI

Question 48.
Alkyl halides react with metallic sodium in dry ether producing
(a) alkanes with same number of carbon atoms
(b) alkanes with double the number of carbon atoms
(c) alkenes with triple the number of carbon atoms
(d) alkenes with same number of carbon atoms
Answer:
(b) alkanes with double the number of carbon atoms

Question 49.
On treating a mixture of two alkyl halides with sodium metal in dry ether, 2-methylpropane was obtained. The alkyl halides are
(a) 2-chloropropana and choromethane
(b) 2-chloropropane and chloroethane
(c) chloromethane and chloroethane
(d) chloromethane and 1-chloropropane
Answer:
(a) 2-chloropropana and choromethane

Question 50.
Chlorobenzene on treatment with sodium in dry ether gives diphenyl. The name of the reaction is
(a) Fitting reaction
(b) Wurtz-Fitting reaction
(c) Sandmeyer reaction
(d) Gattermann reaction
Answer:
(a) Fitting reaction

Question 51.
Aryl halides are less reactive towards nucleophilic substitution reactions as compared to alkyl halides due to
(a) formation of a less stable carbonium ion in aryl halides
(b) resonance stabilisation in aryl halides
(c) presence of double bonds in alkyl halides
(d) inductive effect in aryl halides
Answer:
(b) resonance stabilisation in aryl halides

Question 52.
The end product (Q) in the following sequence of reactions is

Answer:
(c)

Question 53.
Chloroform is kept in dark coloured bottles because
(a) it reacts with clear glass
(b) it undergoes chlorination in transparent glass bottles
(c) it is oxidised to poisonous gas, phosgene in sunlight
(d) it starts burning when exposed to sunlight
Answer:
(c) it is oxidised to poisonous gas, phosgene in sunlight

Question 54.
Triiodomethane has antiseptic property because of
(a) liberation of iodoform
(b) liberation of free iodine
(c) formation of phosgene gas
(d) none of these
Answer:
(b) liberation of free iodine

Question 55.
The fire extinguisher ‘pyrene’ contains
(a) Carbon dioxide
(b) Carbon disulphide
(c) Carbon tetrachloride
(d) Chloroform
Answer:
(c) Carbon tetrachloride

Question 56.
An organic halogen compound which is used as refrigerant in refrigerators and air conditioners is (a)BHC
(b) CCl₄
(c) freon
(d) CHCl₃
Answer:
(c) freon

Question 57.
Which one is correct ?
(a) Freon-14 is CF₄, Freon-13 is CF₃Cl, Freon-13 is CF₂Cl₂ and Freon-11 is CFCl₃
(b) Freons are chlorofluorocarbons
(c) Freons are used as refrigerants
(d) All the above
Answer:
(d) All the above

Question 58.
Toluene reacts with a halogen in the presence of iron (III) chloride giving ortho and para halo compounds. The reaction is
(a) electrophilic elimination reaction
(b) electrophilic substitution reaction
(c) free radical addition reaction
(d) nucleophilic substitution reaction
Answer:
(b) electrophilic substitution reaction

Question 59.
Which reagent will you use for the following reaction ?
CH₃CH ₂CH₂CH₃ → CH₃CH ₂CH₂CH₂CI + CH₃CH₂CHCICH₃
(a) Cl₂/UV light
(b) NaCl + H₂SO₄
(c) Cl₂ gas in dark
(d) Cl₂ gas in the presence of iron in dark
Answer:
(a) Cl₂/UV light

Question 60.
Which of the following is an example of vic-dihalide ?
(a) Dichloromethane
(b) 1, 2-Dichloroethane
(c) Ethylidene chloride
(d) Allyl chloride
Answer:
(b) 1, 2-Dichloroethane

Question 61.
The position of – Br in the compound in CH₃CH = CHC(Br) (CH₃)₂ can be classified as………………….
(a) allyl
(b) aryl
(c) vinyl
(d) secondary
Answer:
(a) allyl

Question 62.
Ethylidene chloride is a/an……………
(a) vic-dihalide
(b) gem-dihalide
(c) allylic halide
(d) vinylic halide
Answer:
(b) gem-dihalide

Question 63.
A primary alkyl halide would prefer to undergo……………..
(a) S_N1 reaction
(b) S_N2 reaction
(c) a-elimination
(d) racemisation
Answer:
(b) S_N2 reaction

Question 64.
Which of the following alkyl halides will undergo S_N1 reaction most readily ?
(a) (CH₃)₃C – F
(b) (CH₃)₃ C- Cl
(c) (CH₃)₃ C – Br
(d) (CH₃)₃ C – I
Answer:
(d) (CH₃)₃ C – I

Question 65.
Which is the correct IUPAC name for

(a) 1- Bromo-2-ethylpropane
(b) 1 – Bromo-2-ethyl-2-methylethane
(c) 1- Bromo-2-methylbutane
(d) 2-Methyl- 1-bromobutane
Answer:
(c) 1- Bromo-2-methylbutane

Question 66.
hat should be the correct IUPAC name for diethylbromomethane ?
(a) 1-Bromo-1, 1-diethylmethane
(b) 3-Bromopentane
(c) 1-Bromo-1-ethylpropane
(d) 1-Bromopentane
Answer:
(b) 3-Bromopentane

Question 67.
The reaction of toluene with chlorine in the presence of iron and in the absence of light yields …………….

Answer:
(d)

Question 68.
Molecules whose mirror image is non superimposable over them are known as chiral. Which of the following molecules is chiral in nature ?
(a) 2-Bromobutane
(b) 1-Bromobutane
(c) 2-Bromopropane
(d) 2-Bromopropan-2-ol
Answer:
(a) 2-Bromobutane

Question 69.
Which is the corret inreasing order of boiling points of the following compounds ?
1-Bromoethane, 1-Bromopropane, 1-Bromobutane, Bromobenzene
(a) Bromobenzene < 1 -Bromobutane < 1 -Bromopropane
< 1-Bromothane
(b) Bromobenzene < 1-Bromothane < 1-Bromopropane
< 1-Bromobutane
(c) 1-Bromopropane < 1-Bromobutane < 1-Bromothane
< Bromobenzene
(d) 1 -Bromoethane < 1 -Bromopropane < 1-Bromobutane
< Bromobenzene
Answer:
(d) 1 -Bromoethane < 1 -Bromopropane < 1-Bromobutane
< Bromobenzene