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Friday, 9 October

JEE Main 2021 · ChemistryMultiple choiceSingle correctHardMulti-step

JEE Main 25 July 2021, Shift 1, Chemistry Q43

Question 43 of 90 in this shift, Chemistry question 13 of 30, Section A.

[figure: but-3-en-2-one, CH2=CH-C(=O)-CH3, treated with (i) C2H5MgBr\mathrm{C_2H_5MgBr}, dry ether (ii) H2O\mathrm{H_2O}, HCl giving P (Major Product)] Consider the above reaction, the major product 'P' is :

The figure, in words

Reaction scheme: methyl vinyl ketone with C2H5MgBr in dry ether then H2O, HCl gives P.
  1. (1)[figure: ClCH2CH2-C(OH)(CH3)-CH2CH3]
  2. (2)[figure: CH3-CH(Cl)-C(OH)(CH3)-CH2CH3]Official answer
  3. (3)[figure: long-chain tertiary alcohol CH3(CH2)4-C(OH)(CH3)-CH2CH3]
  4. (4)[figure: CH2=CH-C(OH)(CH3)-CH2CH3]

Official answer

Option 2

NTA final key.

Chapter
Aldehydes, Ketones and Carboxylic Acids
Topic
Nucleophilic Addition
Idea tested
Grignard Addition to Alpha,Beta-Unsaturated Carbonyls

Same topic in other shifts

All Nucleophilic Addition questions
  1. 2 Apr 2026, Shift 2 · Q67A molecule (X) with following structure under mild acidic condition is hydrolysed to produce (Y) and (Z). Identify the correct statements…MediumSingle correct
  2. 5 Apr 2026, Shift 2 · Q66Given below are two statements : Statement I : The condensation reaction between CH3−CH=O\mathrm{CH_3-CH=O} and H2N−NH−C(=O)−NH2\mathrm{H_2N-NH-C(=O)-NH_2}…MediumTwo statements
  3. 7 Apr 2025, Shift 2 · Q68"P" is an optically active compound with molecular formula C6H12O\mathrm{C_6H_{12}O}. When 'P' is treated with 2, 4-dinitrophenylhydrazine, it…MediumDiagram basedHas a figure
  4. 6 Apr 2024, Shift 2 · Q78Consider the given reaction, identify the major product P. CH3−COOH\mathrm{CH_3-COOH}…MediumSingle correct
  5. 31 Jan 2024, Shift 1 · Q89The product of the following reaction is P. 4-Hydroxybenzaldehyde, (i) PhMgBr (1 equiv.), (ii) aq. NH4Cl\mathrm{NH_4Cl}, gives P The number…MediumNumerical valueHas a figure
  6. 24 Jun 2022, Shift 1 · Q89Number of electrophilic centres in the given compound is ______.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 42 of the 174 JEE Main shifts held from 2017 to 2026.