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JEE Main 2026 Jan 21 Shift 1, Chemistry Q11: Properties and Important Reactions of Aldehydes & Ketones

JEE Main2026Jan 21, Shift 1Chemistry
Q.

An organic compound "P" of molecular formula gives positive Iodoform test but negative Tollen's test. When "P" is treated with dilute acid, it produces "Q". "Q" gives positive Tollen's test and also iodoform test. The structure of "P" is:

  1. A
  2. B
  3. C
  4. D
Solution

P must have a methyl ketone group (for iodoform positive) and be a non-aldehyde (Tollen's negative). On hydrolysis with dil. acid, the dimethyl acetal of P breaks down to give an aldehyde Q that is also a methyl ketone (gives iodoform), i.e., contains and methyl ketone in same molecule.

Option (2) matches: methyl ketone + dimethyl acetal of an aldehyde.

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