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Saturday, 31 October

JEE Main 2023 · ChemistryMultiple choiceOtherMediumMulti-step

JEE Main 10 April 2023, Shift 1, Chemistry Q73

Question 73 of 90 in this shift, Chemistry question 13 of 30, Section A.

Identify the correct order of reactivity for the following pairs towards the respective mechanism (A) SN2\mathrm{S_N2} [structure: (CH3)2CHCH2Br(\mathrm{CH_3})_2\mathrm{CHCH_2Br} (isobutyl bromide, skeletal)] > [structure: (CH3)3CBr(\mathrm{CH_3})_3\mathrm{CBr} (tert-butyl bromide, skeletal)] (B) SN1\mathrm{S_N1} [structure: benzyl bromide, C6H5CH2Br\mathrm{C_6H_5CH_2Br}] > [structure: 2-phenylethyl bromide, C6H5CH2CH2Br\mathrm{C_6H_5CH_2CH_2Br}] (C) Electrophilic substitution [structure: chlorobenzene] > [structure: 4-nitrochlorobenzene (Cl and NO2\mathrm{NO_2} para)] (D) Nucleophilic substitution [structure: bromobenzene] < [structure: 4-nitrobromobenzene (Br and NO2\mathrm{NO_2} para)] Choose the correct answer from the options given below:

The figure, in words

Four pairs of skeletal structures: (A) isobutyl bromide > tert-butyl bromide (SN2); (B) benzyl bromide > 2-phenylethyl bromide (SN1); (C) chlorobenzene > 4-nitrochlorobenzene (electrophilic substitution); (D) bromobenzene < 4-nitrobromobenzene (nucleophilic substitution).
  1. (1)(B), (C) and (D) only
  2. (2)(A), (B) and (D) only
  3. (3)(A), (C) and (D) only
  4. (4)(A), (B), (C) and (D)Official answer

Official answer

Option 4

NTA final key.

Chapter
Haloalkanes and Haloarenes
Topic
SN1 and SN2 Mechanisms
Idea tested
Substrate Steric Effects

Same idea in other shifts

Asked 3× in all
  1. 8 Apr 2024, Shift 1 · Q77Which among the following compounds will undergo fastest SN2\mathrm{S_N2} reaction.EasyDiagram basedHas a figure
  2. 4 Sep 2020, Shift 1 · Q41The decreasing order of reactivity of the following organic molecules towards AgNO3\mathrm{AgNO_3} solution is :HardDiagram basedHas a figure

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.