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Saturday, 31 October

JEE Main 2022 · ChemistryMultiple choiceDiagram basedHardMulti-step

JEE Main 28 June 2022, Shift 2, Chemistry Q76

Question 76 of 90 in this shift, Chemistry question 16 of 30, Section A.

Isobutyraldehyde on reaction with formaldehyde and K2CO3\mathrm{K_2CO_3} gives compound ‘A’. Compound ‘A’ reacts with KCN and yields compound ‘B’, which on hydrolysis gives a stable compound ‘C’. The compound ‘C’ is

The figure, in words

All four options are drawn structures: A and B open-chain hydroxy acids, C and D five-membered lactone rings.
  1. (1)[figure: open chain HO-CH2_2-C-CH-COOH; CH3_3 drawn above the C; below the C and CH two vertical bonds ending in the printed label "CH3_3OH"]
  2. (2)HO−CH2CH2−CH−CH−COOH\mathrm{HO-CH_2CH_2-CH-CH-COOH} with CH3_3 drawn below the first CH and OH drawn below the second CH
  3. (3)[figure: five-membered lactone ring (ring O, C=O carbon); ring carbon next to the C=O bears HO; next ring carbon bears two H3C groups; then ring CH2 bonded to the ring O]Official answer
  4. (4)[figure: five-membered lactone ring (ring O, C=O carbon); ring carbon next to the C=O bears two H3C groups; next ring carbon bears HO; then ring CH2 bonded to the ring O]

Official answer

Option 3

NTA final key.

Same idea in other shifts

Asked 3× in all
  1. 4 Apr 2024, Shift 1 · Q78Given below are two statements : Statements I : Acidity of α\alpha-hydrogens of aldehydes and ketones is responsible for Aldol reaction.…MediumTwo statements
  2. 25 Jul 2021, Shift 1 · Q44[figure: 3,3-dimethylcyclopentanone (ketone C=O, gem-dimethyl on adjacent ring carbon) reacts with CH3CHO\mathrm{CH_3CHO}, NaOH to give 'P'…HardSingle correctHas 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.