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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceDiagram basedMediumApplication

JEE Main 24 February 2021, Shift 1, Chemistry Q45

Question 45 of 90 in this shift, Chemistry question 15 of 30, Section A.

Identify products A and B. [figure] →273 Kdil. KMnO4A→CrO3B\xrightarrow[273\ \mathrm{K}]{\mathrm{dil.\ KMnO_4}} \mathrm{A} \xrightarrow{\mathrm{CrO_3}} \mathrm{B}

The figure, in words

Stem structure: five-membered ring with CH3 on one ring carbon; a double bond is drawn between that ring carbon and the ring carbon below it. Reagent over first arrow: dil. KMnO4, 273 K; over second arrow: CrO3.
  1. (1)A: [figure: five-membered ring with one ring carbon bearing CH3 and OH, and the adjacent ring carbon bearing OH] B: [figure: five-membered ring with CH3 on one ring carbon; a ring double bond between that carbon and its upper ring neighbour, and its other ring neighbour (below) drawn as C=O]
  2. (2)A: [figure: five-membered ring with one ring carbon bearing CH3 and OH, and the adjacent ring carbon bearing OH] B: [figure: five-membered ring with one ring carbon bearing CH3 and OH, and the adjacent ring carbon drawn as C=O]Official answer
  3. (3)A: [figure: five-membered ring with one ring carbon bearing CH3 and the adjacent ring carbon bearing OH] B: [figure: five-membered ring with one ring carbon bearing CH3 and the adjacent ring carbon drawn as C=O]
  4. (4)A : OHC−CH2CH2CH2−C(=O)−CH3\mathrm{OHC{-}CH_2CH_2CH_2{-}C(=O){-}CH_3} B : HOOC−CH2CH2CH2−C(=O)−CH3\mathrm{HOOC{-}CH_2CH_2CH_2{-}C(=O){-}CH_3} [figure: C=O drawn above the carbon bonded to CH3 in each]

Official answer

Option 2

NTA final key.

Same idea in other shifts

Asked 2× in all
  1. 29 Jun 2022, Shift 2 · Q89In the given reaction, [figure: six-membered ring of single bonds with an HO group attached; reagents over the arrow: (i)…MediumNumerical valueHas 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.