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Saturday, 31 October

JEE Main 2024 · ChemistryMultiple choiceDiagram basedMediumApplication

JEE Main 29 January 2024, Shift 1, Chemistry Q74

Question 74 of 90 in this shift, Chemistry question 14 of 30, Section A.

Identify product A and product B :

The figure, in words

Reaction scheme: cyclohexene + Cl2 gives Product A under h u (upper arrow) and Product B in CCl4 (lower arrow). Options are pairs of dichloro structures A and B.
  1. (1)[figure: A = 3,6-dichlorocyclohexene (Cl at the two para ring carbons, ring C=C between the other two carbons on one side); B = 1,2-dichlorocyclohexane (vicinal Cl)]Official answer
  2. (2)[figure: A = 3,6-dichlorocyclohexene; B = 3,6-dichlorocyclohexene (same type of structure as A)]
  3. (3)[figure: A = 1,2-dichlorocyclohexane; B = 1,2-dichlorocyclohexane]
  4. (4)[figure: A = 1,2-dichlorocyclohexane; B = 3,6-dichlorocyclohexene]

Official answer

Option 1

NTA final key.

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

Same idea in other shifts

Asked 3× in all
  1. 28 Jun 2022, Shift 2 · Q89The major product of the following reaction contains __________ bromine atom(s). [reaction: structure →hνBr2\xrightarrow[h\nu]{\mathrm{Br_2}}…MediumNumerical valueHas a figure
  2. 16 Mar 2021, Shift 2 · Q44[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…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 108 of the 174 JEE Main shifts held from 2017 to 2026.