JEE Main · 2024 · 29 Jan 2024 · Shift 1 · Aldehydes Ketones and Carboxylic Acids

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From the compounds given below, number of compounds which give positive Fehling's test is ____.

Benzaldehyde, Acetaldehyde, Acetone, Acetophenone, Methanal, 4-nitrobenzaldehyde, cyclohexane carbaldehyde.

Answer: 3

Solution

Fehling's test is positive for aliphatic aldehydes; aromatic aldehydes and ketones do not respond.

Benzaldehyde -- aromatic, negative. Acetaldehyde -- aliphatic aldehyde, positive. Acetone, Acetophenone -- ketones, negative. Methanal (HCHO) -- aliphatic aldehyde, positive. 4-nitrobenzaldehyde -- aromatic, negative. Cyclohexanecarbaldehyde -- an aliphatic-type aldehyde, positive.

Positive count: Acetaldehyde, Methanal, cyclohexanecarbaldehyde = 3.

Key confirmed: 3.

Structure Structure of cyclohexane carbaldehyde — Structure of cyclohexane carbaldehyde

JEE Main · 2024 · 29 Jan 2024 · Shift 1 · Integer answer

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