Question

An organic compound ${}^{\prime }{A}^{\prime }$ burns with a sooty flame. It is negative towards Tollen's reagent test and positive for Borsche's reagent test. The compound ${}^{\prime }{A}^{\prime }$ is

• A. Benzaldehyde
• B. Acetophenone
• C. Acetone
• D. Salicylic acid

Answer 1

Answer: (B)

Since given compound ' $A$ ' burns with sooty flame, therefore it must be an aromatic compound. Again when it reacts with Borsche's reagent (acidic $2,4$ -dinitrophenyl hydrazine solution), it yields orange precipitate. Therefore it must be a carbonyl compound, i.e., aldehyde, or ketone. But '$A$' does not perform Tollen's reagent test therefore, it must be an aromatic ketone.

Hence, ' $A$ ' is acetophenone.