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2,4-DNP test can be used to identify:

1. Amine
2. Aldehyde
3. Ether
4. Halogens

Correct answer: Aldehyde

Solution

2,4-Dinitrophenylhydrazine (Brady's reagent) reacts with the C=O group of aldehydes and ketones to give orange/yellow hydrazone precipitates. It is a test for carbonyl compounds; among the options it identifies the aldehyde. Amines, ethers and halogens give no such reaction.

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