JEE Main 2026 Apr 5 Shift 2, Chemistry Q16: Properties and Important Reactions of Aldehydes & Ketones

JEE Main2026Apr 5, Shift 2Chemistry

Given below are two statements:

Statement-I: The condensation reaction between $C H_{3} - C H = O$ and under optimum pH will produce

Statement-II: The molecule will generate $P h - C H = O$ in the presence of dilute acid.

In the light of the above statements, choose the correct answer from the options given below:

A
Both Statement-I and Statement-II are true.
B
Both Statement-I and Statement-II are false.
C
Statement-I is true but Statement-II is false.
D
Statement-I is false but Statement-II is true.

Solution

Statement-I: In semicarbazide, the terminal $- N H_{2}$ adjacent to $- N H -$ is the more nucleophilic nitrogen (the amide $- N H_{2}$ adjacent to $C = O$ is deactivated by resonance). Condensation with $C H_{3} C H O$ therefore occurs at the hydrazine-end nitrogen, giving $C H_{3} - C H = N - N H - C (= O) - N H_{2}$ . The product shown in the statement attaches the imine nitrogen at the central position, which is the incorrect connectivity. False.

Statement-II: A hemiacetal is in equilibrium with the parent aldehyde and alcohol; in dilute acid the methoxy group is lost as methanol, regenerating $P h - C H O$ . True.

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JEE Main 2026 Apr 5 Shift 2, Chemistry Q16: Properties and Important Reactions of Aldehydes & Ketones

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