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Q.
Which of the following compounds will give a coloured crystalline compound with ?
Aldehydes Ketones and Carboxylic Acids
Solution:
A positive $2,4$ -DNP test means that your unknown contains either an aldehyde or ketone, while a negative test tells you that it doesn't. It's actually the hydrazine group that reacts with the aldehyde or ketone, producing a positive test.
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