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JEE Main

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

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Haloalkanes and Haloarenes

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Q 1.
{tex}Z{/tex} is

A

{tex} \mathrm { CH } _ { 3 } - \mathrm { CH } _ { 3 } {/tex}

B

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

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

D

Explanation

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Q 2. An {tex} S _ { N }1 {/tex} reaction at the asymmetric carbon of an enantiomerically pure chiral alkyl halide gives an product:

A

with retention of configuration

B

with inversion of configuration

with racemisation

D

with partial racemisation

Explanation

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Q 3. Which of the following statements is incorrect for ethylene dichloride and ethylidene chloride?

A

These are structural isomers

B

Both of these yield same product on reaction with alcoholic KOH solution

Both of these yield same product on treatment with aqueous KOH solution

D

Both of these yield same product on reduction

Explanation

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Q 4.
The major product in this reaction is:

B

C

D

Explanation

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Q 5. Arrange the following compound for {tex}{ S _ { N }} { 1 } {/tex} reactivity order:

A

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

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

C

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

D

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

Explanation

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Q 6. The reaction is:

an {tex} \mathrm { S } _ { \mathrm { N } } 1 {/tex} reaction

B

an {tex} \mathrm { S } _ { \mathrm { N } } 2 {/tex} reaction

C

an {tex} \mathrm { S } _ { \mathrm { N } } \mathrm 3{/tex} reaction

D

None of these

Explanation

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Q 7. In the reaction
{tex} \mathrm { R } - \mathrm { COOAg } + \mathrm { Br } _ { 2 } \longrightarrow \mathrm { RBr } + \mathrm { CO } _ { 2 } + \mathrm { AgBr } {/tex}
The reaction proceeds through the intermediate formation of:

A

B

C

All of these

Explanation

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Q 8. Consider the following reaction and select best choice that represents the reaction.

A

B

D

Explanation

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Q 9. The IUPAC name of the compound shown below

A

2-bromo -6-chlorocyclohex-1-ene

B

6-bromo -2-chlorocyclohexene

3-bromo -1-chlorocyclohexene

D

1-bromo -3-chlorocyclohexene

Explanation

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Q 10. Which chloride is least reactive with the hydrolysis point of view ?

A

B

C

Explanation

The halogen atom in vinyl chloride is not reactive as in other alkyl halides. The non-reactivity of chlorine atom is due to resonance stabilisation. The 1.p. on Cl- atom can participate in delocalisation (Resonance) to give two canonical structure

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Q 11. In a SN2 substitution reaction of the type which one of the following has the highest relative rate

A

B

C

Explanation

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Q 12. Which of the following reactions will result in the formation of a chiral centre in the product?

A

{tex} \mathrm { CH } _ { 3 } \mathrm { CH } = \mathrm { CH } _ { 2 } + \mathrm { HBr } \longrightarrow {/tex}

B

{tex} \mathrm { CH } _ { 2 } = \mathrm { CH } _ { 2 } + \mathrm { HOBr } \longrightarrow {/tex}

C

{tex} \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } = \mathrm { CH } _ { 2 } + \mathrm { HBr } \longrightarrow {/tex}

Explanation

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Q 13. The reaction of {tex} ( S ) - 2 {/tex} -bromobutane with {tex} \mathrm { OH } ^ { - } {/tex} to produce (R)-butan-{tex}2{/tex}-ol will be

A

first order in {tex}2{/tex}-bromobutane only

B

first order in {tex} \mathrm { OH } ^ { - } {/tex} only

first order in {tex}2{/tex}-bromobutane and first order in {tex} \mathrm { OH } ^ { - } {/tex}

D

second order in {tex} \mathrm { OH } ^ { - } {/tex}

Explanation

Configuration invert, means SN2 reaction takes place Rate = K [Substrate][OH]

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Q 14. What is the major product of the following reaction?

B

C

D

None of these

Explanation

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Q 15. Consider the reactions:

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

SN1 and SN2

B

SN1 and SN1

C

SN2 and SN2

D

SN2 and SN1

Explanation

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Q 16. Consider the following bromides

The correct order of SN1 reactivity is

B > C > A

B

B > A > C

C

C > B > A

D

A > B > C

Explanation


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Q 17. Aryl halide is less reactive than alkyl halide towards nucleophilic substitution because:

A

of less stable carbonium ion

due to large C-Cl bond energy

C

of inductive effect

D

of resonance stabilization and sp2 hybridization of C attached to halide

Explanation

Aryl halide is less reactive than alkyl halide towards nucleophilic substitution because of the resonance stabilization and sp2 hybridization of C attached to halide. Due to resonance, carbon-chlorine bond acquires partial double bond character, hence it becomes shorter and stronger, and thus, cannot be easily replaced by nucleophiles. This effect is further enhanced by the sp2 nature of the C atom to which chlorine is attached.

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Q 18. Identify {tex} ( \mathrm { X } ): {/tex}

{tex} \mathrm { F } _ { 2 } \mathrm { C } = \mathrm { CF } _ { 2 } {/tex}

B

{tex} \mathrm { ClFC } = \mathrm { CFCl } {/tex}

C

{tex} \mathrm { F } _ { 2 } \mathrm { C } = \mathrm { CFCl } {/tex}

D

{tex} \mathrm { F } _ { 2 } \mathrm { C } = \mathrm { CCl } _ { 2 } {/tex}

Explanation

2CHF2Cl ---> F2C=CF2 + 2HCl

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Q 19. Chloropicrin is a strong lachrymatory compound and is used in war. It is prepared by:

A

heating acetone with chloroform in the presence of dilute NaOH.

heating chloroform with {tex} \mathrm { HNO } _ { 3 } {/tex}

C

heating nitormethane with carbon tetrachloride.

D

the reaction of acetylene and arsenic chloride.

Explanation

Because of the precursor used, Stenhouse named the compound chloropicrin, although the two compounds are structurally dissimilar. Today, chloropicrin is manufactured by the reaction of nitromethane with sodium hypochlorite H3CNO2 + 3 NaOCl → Cl3CNO2 + 3 NaOH or by the reaction of chloroform with nitric acid CHCl3 + HNO3 → CCl3NO2 + H2O