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Saturday, 31 October

JEE Main 2024 · ChemistryMultiple choiceOtherMediumMulti-step

JEE Main 4 April 2024, Shift 1, Chemistry Q76

Question 76 of 90 in this shift, Chemistry question 16 of 30, Section A.

Identify (B) and (C) and how are (A) and (C) related ? (A) = 1-bromo-4-(2-bromoethyl)benzene drawn as 4-Br-C6H4-CH2CH2Br; →NaOH(alc)\xrightarrow{\mathrm{NaOH_{(alc)}}} (B) →EtherHBr\xrightarrow[\mathrm{Ether}]{\mathrm{HBr}} (C) (B) (C)

The figure, in words

Compound (A): benzene ring with Br at one para position and CH2CH2Br chain at the other. Reaction (A) --NaOH(alc)--> (B) --HBr/Ether--> (C). Each option is a pair of drawn structures (B), (C) followed by a relationship label as printed (the printed label in option 2 is 'positon isomers'); options 1 and 4 show the ring with an OH substituent.
  1. (1)(B) = 4-(2-bromoethyl)phenol [HO-C6H4-CH2CH2Br]; (C) = 4-(2-hydroxyethyl)phenol [HO-C6H4-CH2CH2OH]; functional group isomers
  2. (2)(B) = 4-bromostyrene [Br-C6H4-CH=CH2]; (C) = 1-bromo-4-(1-bromoethyl)benzene [Br-C6H4-CH(Br)CH3]; positon isomersOfficial answer
  3. (3)(B) = 4-bromostyrene [Br-C6H4-CH=CH2]; (C) = 1-bromo-4-(2-bromoethyl)benzene [Br-C6H4-CH2CH2Br]; chain isomers
  4. (4)(B) = 4-(2-bromoethyl)phenol [HO-C6H4-CH2CH2Br]; (C) = 4-(1-bromoethyl)phenol [HO-C6H4-CH(Br)CH3]; Derivative

Official answer

Option 2

NTA final key.

Chapter
Haloalkanes and Haloarenes
Topic
Structural Isomerism
Idea tested
Chain vs Position Priority Resolution

Same topic in other shifts

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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.