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Saturday, 31 October

JEE Main 2024 · ChemistryNumerical answerNumerical valueMediumMulti-step

JEE Main 5 April 2024, Shift 2, Chemistry Q89

Question 89 of 90 in this shift, Chemistry question 29 of 30, Section B.

The product (C) in the following sequence of reactions has ________ π\pi bonds. n-propylbenzene (benzene ring bearing a three-carbon chain) →ΔKMnO4−KOH\xrightarrow[\Delta]{\mathrm{KMnO_4-KOH}} (A) →H3O+\xrightarrow{\mathrm{H_3O^+}} (B) →FeBr3Br2\xrightarrow[\mathrm{FeBr_3}]{\mathrm{Br_2}} (C)

The figure, in words

Starting material drawn as a benzene ring with a three-carbon zigzag alkyl chain (propyl group) attached; reagents over arrows: KMnO4−KOH\mathrm{KMnO_4-KOH}, Δ\Delta; then H3O+\mathrm{H_3O^+}; then Br2/FeBr3\mathrm{Br_2/FeBr_3}; intermediates labelled A, B, C.

Official answer

4

NTA final key.

Chapter
Aldehydes, Ketones and Carboxylic Acids
Topic
Aromatic Hydrocarbons
Idea tested
Side-chain Oxidation

Same idea in other shifts

Asked 6× in all
  1. 4 Apr 2026, Shift 1 · Q72Consider the following sequence of reactions to give the major product (X) benzene…MediumNumerical valueHas a figure
  2. 30 Jan 2024, Shift 1 · Q75In the given reactions, identify the reagent A and reagent B. [Scheme: toluene reacts via two routes to give benzaldehyde. Route 1: "A" +…MediumOtherHas a figure
  3. 10 Apr 2023, Shift 1 · Q74The major product ‘P’ formed in the given reaction is [structure: naphthalene ring bearing CH2CH3\mathrm{CH_2CH_3} at one position of one…MediumDiagram basedHas a figure
  4. 26 Jun 2022, Shift 2 · Q72Oxidation of toluene to benzaldehyde can be easily carried out with which of the following reagents?MediumSingle correct
  5. 4 Aug 2021, Shift 1 · Q45Identify P in the given chemical reaction i) KMnO4\mathrm{KMnO_4}, KOH, heat ii) H3O+\mathrm{H_3O^+}EasyDiagram 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.