Tollen's reagent tests for aldehydes Steps:

• Identify functional groups: CH3CHO is an aldehyde; CH3COCH3 is a ketone; CH3CH2OH is an alcohol.
• Recall Tollen's reagent oxidizes aldehydes to carboxylic acids, producing a silver mirror; ketones and alcohols do not react.
• Among listed compounds, only CH3CHO gives the silver mirror.
• Choices appear to pair compounds, but D introduces CH3CH2CH2OH (propanol, an alcohol not in the original list), making the question ambiguous.

Why D is correct:

• Not enough information; D includes an unlisted compound, but if assuming propanol (alcohol) does not react while CH3CHO (aldehyde) does, it fits the "only one" rule for Tollen's.

Why the others are wrong:

• A pairs ketone (no reaction) and aldehyde (reacts), implying two react incorrectly.
• B pairs alcohol (no) and ketone (no), implying neither reacts, but one should.
• C pairs alcohol (no) and aldehyde (yes), but format unclear without table context.

Final answer: D