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Saturday, 31 October

JEE Main 2025 · ChemistryMultiple choiceDiagram basedMediumMulti-step

JEE Main 7 April 2025, Shift 2, Chemistry Q68

Question 68 of 75 in this shift, Chemistry question 18 of 25, Section A.

"P" is an optically active compound with molecular formula C6H12O\mathrm{C_6H_{12}O}. When 'P' is treated with 2, 4-dinitrophenylhydrazine, it gives a positive test. However, in presence of Tollens reagent, "P" gives a negative test. Predict the structure of "P".

The figure, in words

Options are condensed structural formulas (C=O drawn above the carbonyl carbon; branching CH3 / CH2-CH3 drawn below the chain).
  1. (1)CH3−CO−CH2−CH(CH3)−CH3\mathrm{CH_3-CO-CH_2-CH(CH_3)-CH_3}
  2. (2)CH3−CO−CH(CH3)−CH2−CH3\mathrm{CH_3-CO-CH(CH_3)-CH_2-CH_3}Official answer
  3. (3)OHC−CH2−CH(CH3)−CH2−CH3\mathrm{OHC-CH_2-CH(CH_3)-CH_2-CH_3}
  4. (4)CH3−CO−CH2−CH2−CH2−CH3\mathrm{CH_3-CO-CH_2-CH_2-CH_2-CH_3}

Official answer

Option 2

NTA final key.

Chapter
Aldehydes, Ketones and Carboxylic Acids
Topic
Nucleophilic Addition
Idea tested
2,4-DNP (Brady's Reagent) Test

Same idea in other shifts

Asked 2× in all
  1. 26 Feb 2021, Shift 2 · Q492,4-DNP test can be used to identify :EasySingle 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 108 of the 174 JEE Main shifts held from 2017 to 2026.