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Friday, 9 October

JEE Main 2025 · ChemistryMultiple choiceSingle correctMediumMulti-step

JEE Main 8 April 2025, Shift 2, Chemistry Q66

Question 66 of 75 in this shift, Chemistry question 16 of 25, Section A.

Choose the correct set of reagents for the following conversion. Ethyl benzene → [structure: p-bromostyrene, i.e. benzene ring with CH=CH2 and Br at para positions]

The figure, in words

Ethyl benzene converted to a para-disubstituted benzene bearing CH=CH2 at the top and Br at the bottom (4-bromostyrene).
  1. (1)Cl2\mathrm{Cl_2}/anhy.AlCl3\mathrm{AlCl_3} ; Br2\mathrm{Br_2}/Fe ; alc. KOH
  2. (2)Br2\mathrm{Br_2}/Fe ; Cl2\mathrm{Cl_2}, Δ ; alc.KOHOfficial answer
  3. (3)Br2\mathrm{Br_2}/anhy.AlCl3\mathrm{AlCl_3} ; Cl2\mathrm{Cl_2}, Δ ; aq. KOH
  4. (4)Cl2\mathrm{Cl_2}/Fe ; Br2\mathrm{Br_2}/anhy.AlCl3\mathrm{AlCl_3} ; aq. KOH

Official answer

Option 2

NTA final key.

Chapter
Haloalkanes and Haloarenes
Topic
Aromatic Hydrocarbons
Idea tested
Ortho-Para vs Meta Directing

Same idea in other shifts

Asked 3× in all
  1. 2 Apr 2026, Shift 1 · Q66For the given molecule, "xx", the preferred site for the attack of the electrophile is :MediumDiagram basedHas a figure
  2. 24 Jun 2022, Shift 1 · Q73In the given reaction sequence, the major product 'C' is :…MediumSingle correctHas 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 42 of the 174 JEE Main shifts held from 2017 to 2026.