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Friday, 9 October

JEE Main 2021 · ChemistryMultiple choiceDiagram basedMediumApplication

JEE Main 16 March 2021, Shift 2, Chemistry Q44

Question 44 of 90 in this shift, Chemistry question 14 of 30, Section A.

[figure: cyclohexene reacts with reagent A to give 1,4-dichlorocyclohex-2-ene (a cyclohexene ring with Cl on the two ring carbons para to each other, flanking the double bond)] Identify the reagent(s) 'A' and condition(s) for the reaction

The figure, in words

Reaction scheme: cyclohexane-type ring with one double bond (cyclohexene) --A--> six-membered ring with one double bond and a Cl on the top carbon and a Cl on the bottom carbon.
  1. (1)A = Cl2\mathrm{Cl_2} ; dark, Anhydrous AlCl3\mathrm{AlCl_3}
  2. (2)A = HCl, ZnCl2\mathrm{ZnCl_2}
  3. (3)A = Cl2\mathrm{Cl_2} ; UV lightOfficial answer
  4. (4)A = HCl ; Anhydrous AlCl3\mathrm{AlCl_3}

Official answer

Option 3

NTA final key.

Chapter
Hydrocarbons
Topic
Alkenes and Alkynes
Idea tested
Allylic Halogenation with NBS

Same idea in other shifts

Asked 2× in all
  1. 29 Jan 2024, Shift 1 · Q74Identify product A and product B :MediumDiagram 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 42 of the 174 JEE Main shifts held from 2017 to 2026.