Explanation

(b)
Ketone and aldehyde can be distinguished by Tollen’s reagent, Fehling’s solution and Schiff’s reagent.
$CH_{3}COCH_{3}$ (ketone) and $CH_{3}CH_{2}CHO$(aldehyde) can be distinguised by Tollen’s reagent.$CH_{3}CH_{2}CHO$ reacts with Tollen’s reagent to give silver mirror while $CH_{3}COCH_{3}$ does not react.
$CH_{3}CH_{2}CHO + Ag_{2}O\overset{\ \ \ \ \mathrm{\Delta}\ \ \ \ \ }{\rightarrow}CH_{3}CH_{2}COOH + 2Ag$
Silver
mirror
$CH_{3}COCH_{3} + Ag_{2}O\overset{\ \ \ \ \ \mathrm{\Delta}\ \ \ \ \ }{\rightarrow}$ No reaction