Identify $X$ and $Y$ in the following reactions:

The product $(D)$ in the following reaction sequence is: $HOCH_2CH_2CH_2COOCH_2CH_3$ $\xrightarrow{PCC} (A)$ $\xrightarrow[{(1 \ molar \ equivalent)}]{H_2C=CHMgBr} (B)$ $\xrightarrow{NH_4Cl/H_2O} (C)$ $\xrightarrow[H_2O]{KOH}$ $\xrightarrow{H_3O^{+}}$ $\xrightarrow[pyridine]{(CH_3CO)_2O} (D)$

Identify the product $B$ in the following series of reaction.
$CH_3COOH + CH_3CH_2OH \rightleftharpoons{H^{+}} CH_3COOCH_2CH_3{_{\text{(A)}}} \xrightarrow[Ni/Pd, \Delta]{H_2} CH_3CH_2OH + CH_3CH_2OH{_{\text{(B)}}}$

Which among the following compounds has the highest boiling point?

Oxalic acid on being heated up to $90^\circ C$ with conc. $H_2SO_4$ forms:

Which of the following does not react with a Grignard reagent?