Diethyl amine is a secondary amine and ethyl amine is a primary amine. Primary amines give the carbylamine test with CHCl3 and KOH on heating, while secondary amines do not. Thus, A matches with II.
Acetaldehyde is an aldehyde and acetone is a ketone. Aldehydes reduce ammoniacal silver nitrate (Tollens' reagent) to form a silver mirror, while ketones do not. Thus, B matches with IV.
Phenol reacts with neutral FeCl3 to form a violet-colored complex, whereas ethanol does not react. Thus, C matches with III.
Cinnamic acid contains a carbon-carbon double bond which decolorizes bromine water, whereas benzoic acid does not react with bromine water. Thus, D matches with I.
The correct matching is A-II, B-IV, C-III, D-I.
Answer: A-II, B-IV, C-III, D-I