Which of the following gives positive Tollens test?
(A) Phenylethanal
(B) Acetophenone
(C) Formic acid
(D) Benzene carbaldehyde
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (A), (C) and (D) only
Tollens’ reagent gives a silver mirror test with aldehydes and with compounds that can be easily oxidized to carbon dioxide, such as formic acid. Ketones generally do not give Tollens’ test.
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(A) Phenylethanal – It is an aldehyde, so it reduces Tollens’ reagent and gives a positive test.
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(B) Acetophenone – It is a ketone, and ketones do not reduce Tollens’ reagent, so the test is negative.
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(C) Formic acid – It behaves like an aldehyde and is oxidized to CO₂, therefore it gives a positive Tollens’ test.
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(D) Benzene carbaldehyde (benzaldehyde) – It is an aromatic aldehyde, so it gives a positive Tollens’ test.
Therefore, compounds (A), (C), and (D) give a positive Tollens test.