One of the products of the following reaction is $P$. Structure of $P$ is

$CH_3-CHO$ $\xrightarrow{HCN} (A)$ $\xrightarrow{H_3O^{+}} (B)$ $\xrightarrow{\Delta} (C)$ $\xrightarrow{LiAlH_4} (D)$ $\xrightarrow{HIO_4} HCHO + (E)$. Compound $(C)$ can show geometrical isomerism. Product $(E)$ of the reaction will be:

Reduction of ketones cannot be carried out with which of the following reagents?

Base-catalyzed aldol condensation occurs with:

The major product $(A)$ is:

Which of the following compounds reacts with $50\%$ sodium hydroxide solution to give the corresponding alcohol and acid?