b
\(\mathrm{CH}_{3} \mathrm{CHO}\) and \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2} \mathrm{CHO}\) are aliphatic aldehydes and hence react with Tollen's reagent,

Febling-solution and Benedict solution. These reagents cannot be used to distinguish them

\(C H_{3} C H O\) reacts with \(N a O H\) and \(I_{2}\) to form yellow crystalline iodoform while \(C_{6} H_{5} C H_{2} C H O\)

does not react with it. \(\mathrm{CH}_{3} \mathrm{CHO}+3 \mathrm{I}_{2}+4 \mathrm{NaOH} \longrightarrow \)\(\mathrm{CHI}_{3}\) (Yellow crystalline ppt) \( +3 \mathrm{NaI}+3 \mathrm{H}_{2} \mathrm{O}\)

\(C_{6} H_{5} C H_{2} C H O+3 I_{2}+4 N a O H \rightarrow N\) oreaction

\(\therefore\)         lodoform test can be used to distinguish between \(C H_{3} C H O\) and \(C_{6} H_{5} C H_{2} C H O\)