JEE Main 2026 — Aldehydes and Ketones Question with Solution
JEE Main 2026 (21 January Shift 1)
Question
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 :
Choose an option
Show full solutionCorrect option: A
Correct answer
A
Step-by-step explanation
P gives positive iodoform (has ) but negative Tollen's (no ).
Q (after acid hydrolysis) gives both tests, meaning Q has both and .
This indicates P has an acetal protecting an aldehyde group.
Option (1):
Has → positive iodoform
Has acetal , no free aldehyde → negative Tollen's
Hydrolysis:
Q = gives both iodoform and Tollen's test
Molecular formula:
Q (after acid hydrolysis) gives both tests, meaning Q has both and .
This indicates P has an acetal protecting an aldehyde group.
Option (1):
Has → positive iodoform
Has acetal , no free aldehyde → negative Tollen's
Hydrolysis:
Q = gives both iodoform and Tollen's test
Molecular formula:
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This is a previous-year question from JEE Main 2026, covering the Aldehydes and Ketones chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.