Compound $Y$ must give iodoform test. Further since $Y$ is obtained by the oxidation of $X$ which must be an alcohol $(CH_3CH_2OH)$ and thus $Y$ is $CH_3CHO$
${C_2}{H_5}OH + SOC{l_2}\xrightarrow{{{\text{Pyridine}}}}{C_2}{H_5}Cl + S{O_2} + HCl$

$(I)\,\begin{array}{*{20}{c}}
{C{H_3}CHC{H_2}C{H_3}} \\
{|\,\,\,\,\,\,\,\,\,\,\,} \\
{Cl\,\,\,\,\,\,\,\,\,}
\end{array}$
$(II)\,CH_3CH_2CH_2Cl$
$(III)\,H_3CO-C_6H_4-CH_2Cl$
