Which compound is soluble in $H_2O$?

Find out the reactivity order of the labeled functional groups towards $LiAlH_4$ reduction.

An optically active alkyl bromide $C_4H_9Br$ reacts with ethanolic $KOH$ to form major compound $[A]$, which reacts with bromine to give compound $[B]$. Compound $[B]$ reacts with ethanolic $KOH$ and sodamide to give compound $[C]$. One molecule of water adds to compound $[C]$ on warming with mercuric sulphate and dilute sulphuric acid at $333 \text{ K}$ to form compound $[D]$. The functional group in compound $[D]$ will be confirmed by:

What are $X$ and $Y$ in the following reaction sequence?
$Propene$ $\xrightarrow{HBr} A$ $\xrightarrow[Dry \ ether]{Mg} B$ $\xrightarrow[2. H_3O^{+}]{1. X} Y$

The product $(A)$ of the reaction is:

Write a note on the addition of sodium hydrogen sulphite $(NaHSO_3)$ to the carbonyl group.