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Haloalkanes and Haloarenes

JEE Main 2025 (Online) 2nd April Evening ShiftNumericalEasy📈 Topic in 15% papers+4
Ques. 1JEE Main 2025, 2 April (Evening Shift)

[figure] Consider the above sequence of reactions. 151 g of 2-bromopentane is made to react. Yield of major product P is 80\% whereas Q is 100\%. Mass of product Q obtained is g. (Given molar mass in g mol-1 H : 1, C : 12, O : 16, Br : 80)

Answer

184

Solution

The molar mass of 2-bromopentane, C5H11Br, is 60 + 11 + 80 = 151 g mol-1, so 151 g = 1 mol.

Dehydrohalogenation with alcoholic KOH follows Saytzeff rule, so the more substituted alkene, pent-2-ene, is the major product P:

CH3-CH(Br)-CH2-CH2-CH3 alc. KOH CH3-CH=CH-CH2-CH3

Hence moles of P = 1 0.80 = 0.80 mol.

Addition of bromine then gives 2,3-dibromopentane (Q):

CH3-CH=CH-CH2-CH3 Br2 CH3-CH(Br)-CH(Br)-CH2-CH3

The molar mass of Q, C5H10Br2, is 60 + 10 + 160 = 230 g mol-1.

mass of Q = 0.80 230 = 184 g

Answer: 184

Keep practising — Haloalkanes and Haloarenes

Ques. 2JEE Main 2025, 29 January (Morning Shift)

In the following substitution reaction : [figure] Product 'P' formed is :

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 3JEE Main 2025, 29 January (Evening Shift)

Which among the following halides will generate the most stable carbocation in the nucleophilic substitution reaction?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 4JEE Main 2025, 28 January (Morning Shift)

The products A and B in the following reactions, respectively are A AgNO2 CH3-CH2-CH2-Br AgCN B

  1. CH3-CH2-CH2-ONO, CH3-CH2-CH2-CN
  2. CH3-CH2-CH2-NO2, CH3-CH2-CH2-CN
  3. CH3-CH2-CH2-ONO, CH3-CH2-CH2-NC
  4. CH3-CH2-CH2-NO2, CH3-CH2-CH2-NC
Ques. 5JEE Main 2025, 28 January (Morning Shift)

Given below are two statements : In the light of the above statements, choose the most appropriate answer from the options given below

  1. Both Statement I and Statement II are correct
  2. Statement I is incorrect but Statement II is correct
  3. Both Statement I and Statement II are incorrect
  4. Statement I is correct but Statement II is incorrect
Ques. 6JEE Main 2025, 28 January (Evening Shift)

The product B formed in the following reaction sequence is: [figure]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 7JEE Main 2025, 28 January (Evening Shift)

The major product of the following reaction is: [figure]

  1. 6-Phenylhepta-3,5-diene
  2. 6-Phenylhepta-2,4-diene
  3. 2-Phenylhepta-2,4-diene
  4. 2-Phenylhepta-2,5-diene
Ques. 8JEE Main 2025, 24 January (Morning Shift)

Given below are two statements: In the light of the above statements, choose the correct answer from the options given below

  1. Statement I is false but Statement II is true
  2. Statement I is true but Statement II is false
  3. Both Statement I and Statement II are false
  4. Both Statement I and Statement II are true
Ques. 9JEE Main 2025, 24 January (Evening Shift)

The structure of the major product formed in the following reaction is : [figure]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 10JEE Main 2025, 23 January (Morning Shift)

Match the List - I with List - II Choose the correct answer from the options given below:

  1. A-II, B-III, C-I, D-IV
  2. A-II, B-I, C-III, D-IV
  3. A-IV, B-I, C-III, D-II
  4. A-IV, B-III, C-I, D-II
Ques. 11JEE Main 2025, 23 January (Evening Shift)

The ascending order of relative rate of solvolysis of following compounds is : [figure]

  1. (C) < (D) < (B) < (A)
  2. (D) < (A) < (B) < (C)
  3. (D) < (B) < (A) < (C)
  4. (C) < (B) < (A) < (D)

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