$CH_3-CO-CH_2-COOH$ $\xrightarrow{\Delta} X$ $\xrightarrow[OH^-]{HCN} Y$,$Y$ is:

The end product $(C)$ in the following sequence of reactions is:
$HC \equiv CH$ $\xrightarrow[20\% \ H_2SO_4]{1\% \ HgSO_4} A$ $\xrightarrow[H_2O]{CH_3MgX} B$ $\xrightarrow{[O]} (C)$

Identify the main product of the following reaction: $R - CO - O - R' \xrightarrow[H_3O^+]{DIBAL-H} \text{Product}$

$A$ mixture of benzaldehyde and formaldehyde on heating with aqueous $NaOH$ solution gives :-

The major product of the following reaction is:

The reaction is given as follows: $(CH_3)_2CHCHO + CH_3MgBr$ $\xrightarrow{Ether} A$ $\xrightarrow{H_3O^+} B$. The $IUPAC$ name of $B$ is: