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Friday, 9 October

JEE Main 2025 · ChemistryMultiple choiceSingle correctMediumMulti-step

JEE Main 8 April 2025, Shift 2, Chemistry Q65

Question 65 of 75 in this shift, Chemistry question 15 of 25, Section A.

1,2-dibromocyclooctane →(ii) NaNH2 (iii) Hg2+/H+ (iv) Zn–Hg / H+(i) KOH (alc.)\xrightarrow[\text{(ii) NaNH}_2\ \text{(iii) Hg}^{2+}/\text{H}^+\ \text{(iv) Zn–Hg / H}^+]{\text{(i) KOH (alc.)}} P (major product) 'P' is

The figure, in words

Reaction scheme: 1,2-dibromocyclooctane treated with (i) KOH (alc.), (ii) NaNH2, (iii) Hg2+/H+, (iv) Zn-Hg/H+ to give P (major product). Options are skeletal structures of eight-membered rings.
  1. (1)[figure: cyclooctanone (eight-membered ring with C=O)]
  2. (2)[figure: cyclooctanol (eight-membered ring with OH)]
  3. (3)[figure: cyclooctane (eight-membered ring, no substituent)]Official answer
  4. (4)[figure: cyclooctyne (eight-membered ring with a C≡C triple bond)]

Official answer

Option 3

NTA final key.

Chapter
Haloalkanes and Haloarenes
Topic
Alkenes and Alkynes
Idea tested
Double Elimination to Alkynes

Same topic in other shifts

All Alkenes and Alkynes questions
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  2. 4 Apr 2026, Shift 2 · Q64Compound (X) is subjected to the sequence of reactions as shown above. Molar mass of the major product (Y) formed is ________…MediumDiagram basedHas a figure
  3. 5 Apr 2026, Shift 1 · Q64"P" is a hydrocarbon of molecular formula:- C8H14\mathrm{C_8H_{14}}. On ozonolysis, "P" forms "Q". "Q" on treatment with alkali under reflux…HardDiagram basedHas a figure
  4. 6 Apr 2026, Shift 1 · Q66Given below are two statements: Statement I: 3-phenylpropene reacts with HBr and gives secondary alkyl bromide having a chiral carbon atom…MediumTwo statements
  5. 6 Apr 2026, Shift 2 · Q65An optically active alkyl bromide C4H9Br\mathrm{C_4H_9Br}, reacts with ethanolic KOH to form major compound [A] which reacts with bromine to…MediumSingle correct
  6. 2 Apr 2025, Shift 1 · Q66An optically active alkyl halide C4H9Br\mathrm{C_4H_9Br} [A] reacts with hot KOH dissolved in ethanol and forms alkene [B] as major product…MediumSingle correct

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.