NEET > Haloalkanes and Haloarenes

Explore popular questions from Haloalkanes and Haloarenes for NEET. This collection covers Haloalkanes and Haloarenes previous year NEET questions hand picked by popular teachers.


Q 1.    

Correct4

Incorrect-1

Identify {tex} A {/tex} and predict the type of reaction

A

B

C

Explanation


Q 2.    

Correct4

Incorrect-1

Consider the reaction,
{tex} \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { Br } + \mathrm { NaCN } \rightarrow \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CN }+ \mathrm { NaBr }{/tex}
This reaction will be the fastest in

A

ethanol

B

methanol

{tex} N , N ^ { \prime } {/tex} -dimethylformamide (DMF)

D

water.

Explanation


Q 3.    

Correct4

Incorrect-1

Two possible stereo-structures of {tex} \mathrm { CH } _ { 3 } \mathrm { CHOHCOOH } , {/tex} which are optically active, are called

A

atropisomers

enantiomers

C

mesomers

D

diastereomers.

Explanation

Q 4.    

Correct4

Incorrect-1

In an {tex} \mathrm { S } _ { \mathrm { N } } 1 {/tex} reaction on chiral centres, there is

inversion more than retention leading to partial racemisation

B

100{tex} \% {/tex} retention

C

100{tex} \% {/tex} inversion

D

100{tex} \% {/tex} racemisation.

Explanation


Q 5.    

Correct4

Incorrect-1

The reaction of {tex} \mathrm { C } _ { 6 } \mathrm { H } _ { 5 } \mathrm { CH } = \mathrm { CHCH } _ { 3 } {/tex} with HBr produces

A

{tex} \mathrm { C } _ { 6 } \mathrm { H } _ { 5 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { Br } {/tex}

B

D

Explanation

Q 6.    

Correct4

Incorrect-1

Which of the following compounds will undergo racemisation when solution of {tex} \mathrm { KOH } {/tex} hydrolyses?


A

(i) and (ii)

B

(ii) and (iv)

C

(iii) and (iv)

(i) and (iv)

Explanation

Q 7.    

Correct4

Incorrect-1

Given:

I and II are

A

identical

a pair of conformers

C

a pair of geometrical isomers

D

a pair of optical isomers

Explanation


Q 8.    

Correct4

Incorrect-1

In the replacement reaction

The reaction will be most favourable if {tex} M {/tex} happens to be

A

{tex} \mathrm { Na } {/tex}

B

{tex} \mathbf { K } {/tex}

{tex} \mathrm { Rb } {/tex}

D

{tex} \text { Li} {/tex}

Explanation



Q 9.    

Correct4

Incorrect-1

Consider the reactions.

The mechanisms of reactions (i) and (ii) are respectively

A

{tex} \mathrm { S } _ { \mathrm { N } } 1 {/tex} and {tex} \mathrm { S } _ { \mathrm { N } } 2 {/tex}

B

{tex} \mathrm { S } _ { \mathrm { N } } 1 {/tex} and {tex} \mathrm { S } _ { \mathrm { N } } 1 {/tex}

{tex} \mathrm { S } _ { \mathrm { N } } 2 {/tex} and {tex} \mathrm { S } _ { \mathrm { N } } 2 {/tex}

D

{tex} \mathrm { S } _ { \mathrm { N } } 2 {/tex} and {tex} \mathrm { S } _ { \mathrm { N } } 1 {/tex}

Explanation


Q 10.    

Correct4

Incorrect-1

Which one is most reactive towards {tex} \mathrm { S } _ { \mathrm { N } } 1 {/tex} reaction?

A

{tex} \mathrm { C } _ { 6 } \mathrm { H } _ { 5 } \mathrm { CH } \left( \mathrm { C } _ { 6 } \mathrm { H } _ { 5 } \right) \mathrm { Br } {/tex}

B

{tex} \mathrm { C } _ { 6 } \mathrm { H } _ { 5 } \mathrm { CH } \left( \mathrm { CH } _ { 3 } \right) \mathrm { Br } {/tex}

{tex} \mathrm { C } _ { 6 } \mathrm { H } _ { 5 } \mathrm { C } \left( \mathrm { CH } _ { 3 } \right) \left( \mathrm { C } _ { 6 } \mathrm { H } _ { 5 } \right) \mathrm { Br } {/tex}

D

{tex} \mathrm { C } _ { 6 } \mathrm { H } _ { 5 } \mathrm { CH } _ { 2 } \mathrm { Br } {/tex}

Explanation


Q 11.    

Correct4

Incorrect-1

The correct order of increasing reactivity of

C-X bond towards nucleophile in the following compounds is

{tex} \mathrm { I } < \mathrm { II } < \mathrm { IV } < \mathrm { III } {/tex}

B

{tex} \mathrm { II } < \mathrm { III } < \mathrm { I } < \mathrm { IV } {/tex}

C

{tex} \mathrm { IV } < \mathrm { III } < \mathrm { I } < \mathrm { II } {/tex}

D

{tex} \mathrm { III } < \mathrm { II } < \mathrm { I } < \mathrm { IV } {/tex}

Explanation



Q 12.    

Correct4

Incorrect-1

In the following reaction

A

{tex} \mathrm { C } _ { 6 } \mathrm { H } _ { 5 } \mathrm { CH } _ { 2 } \mathrm { OCH } _ { 2 } \mathrm { C } _ { 6 } \mathrm { H } _ { 5 } {/tex}

B

{tex} \mathrm { C } _ { 6 } \mathrm { H } _ { 5 } \mathrm { CH } _ { 2 } \mathrm { OH } {/tex}

{tex} \mathrm { C } _ { 6 } \mathrm { H } _ { 5 } \mathrm { CH } _ { 3 } {/tex}

D

{tex} \mathrm { C } _ { 6 } \mathrm { H } _ { 5 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { C } _ { 6 } \mathrm { H } _ { 5 } {/tex}

Explanation

Q 13.    

Correct4

Incorrect-1

Which of the following reactions is an example of nucleophilic substitution reaction?

A

{tex} 2 R X + 2 \mathrm { Na } \rightarrow R - R + 2 \mathrm { Na } X {/tex}

B

{tex} R X + \mathrm { H } _ { 2 } \rightarrow R \mathrm { H } + \mathrm { HX } {/tex}

C

{tex} R X + \mathrm { Mg } \rightarrow R \mathrm { Mg } X {/tex}

{tex} R X + \mathrm { KOH } \rightarrow R \mathrm { OH } + \mathrm { KX } {/tex}

Explanation

Q 14.    

Correct4

Incorrect-1

How many stereoisomers does this molecule have?
{tex} \mathrm { CH } _ { 3 } \mathrm { CH } = \mathrm { CHCH } _ { 2 } \mathrm { CHBrCH } _ { 3 } {/tex}

A

8

B

2

4

D

6

Explanation



Q 15.    

Correct4

Incorrect-1

In a {tex} \mathrm { S } _ { \mathrm { N } } 2 {/tex} substitution reaction of the type

which one of the following has the highest relative rate?

A

{tex} \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { Br } {/tex}

C

{tex} \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { Br } {/tex}

D

Explanation


Q 16.    

Correct4

Incorrect-1

If there is no rotation of plane polarised light by a compound in a specific solvent, though to be chiral, it may mean that

the compound is certainly meso

B

there is no compound in the solvent

C

the compound may be a racemic mixture

D

the compound is certainly a chiral.

Explanation


Q 17.    

Correct4

Incorrect-1

Which of the following is not chiral?

A

2 -Hydroxypropanoic acid

B

2 - Butanol

C

2,3 - Dibromopentane

3 -Bromopentane

Explanation



Q 18.    

Correct4

Incorrect-1

Which of the following is least reactive in a nucleophilic substitution reaction?

A

{tex} \left( \mathrm { CH } _ { 3 } \right) _ { 3 } \mathrm { C } - \mathrm { Cl } {/tex}

{tex} \mathrm { CH } _ { 2 } = \mathrm { CHCl } {/tex}

C

{tex} \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { Cl } {/tex}

D

{tex} \mathrm { CH } _ { 2 } = \mathrm { CHCH } _ { 2 } \mathrm { Cl } {/tex}

Explanation





Q 19.    

Correct4

Incorrect-1

Which of the following pairs of compounds are enantiomers?

B

C

D

Explanation


Q 20.    

Correct4

Incorrect-1

Reactivity order of halides for dehydrohalogenation is

A

{tex} R - \mathrm { F } > R - \mathrm { Cl } > R - \mathrm { Br } > R - \mathrm { I } {/tex}

{tex} R - \mathrm { I } > R - \mathrm { Br } > R - \mathrm { Cl } > R - \mathrm { F } {/tex}

C

{tex} R - \mathrm { I } > R - \mathrm { Cl } > R - \mathrm { Br } > R - \mathrm { F }{/tex}

D

{tex} R - \mathrm { F } > R - \mathrm { I } > R - \mathrm { Br } > R - \mathrm { Cl } {/tex}

Explanation


Q 21.    

Correct4

Incorrect-1

{tex} \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { Cl } \stackrel { \mathrm { NaCN } } { \longrightarrow } X \stackrel { \mathrm { Ni } / \mathrm { H } _ { 2 } } { \longrightarrow } Y \stackrel { \text { acetic anhydride } } { \longrightarrow } Z {/tex}
{tex} Z {/tex} in the above reaction sequence is

{tex} \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { NHCOCH } _ { 3 } {/tex}

B

{tex} \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { NH } _ { 2 } {/tex}

C

{tex} \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CONHCH } _ { 3 } {/tex}

D

{tex} \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CONHCOCH } _ { 3 } {/tex}

Explanation



Q 22.    

Correct4

Incorrect-1

obtained by chlorination of {tex} n - {/tex} butane will be

A

meso form

racemic mixture

C

{tex} d - {/tex} form

D

{tex} l - {/tex}form

Explanation


Q 23.    

Correct4

Incorrect-1

An organic compound {tex} A \left( \mathrm { C } _ { 4 } \mathrm { H } _ { 9 } \mathrm { Cl } \right) {/tex} on reaction with Na/diethyl ether gives a hydrocarbon which on monochlorination gives only one chloro derivative then, {tex} A {/tex} is

{tex} t {/tex} -butyl chloride

B

{tex} s {/tex}-butyl chloride

C

{tex} iso {/tex}-butyl chloride

D

{tex} n {/tex} -butyl chloride.

Explanation


Q 24.    

Correct4

Incorrect-1

A compound of molecular formula {tex} \mathrm { C } _ { 7 } \mathrm { H } _ { 16 } {/tex} shows optical isomerism, compound will be

2,3-dimethylpentane

B

2,2 -dimethylbutane

C

2 -methylhexane

D

none of these.

Explanation


Q 25.    

Correct4

Incorrect-1

Ethyl chloride is converted into diethyl ether by

A

Perkins reaction

B

Grignard reaction

C

Wurtz synthesis

Williamson's synthesis

Explanation