Which of the following is boiled with ethyl chloride to form ethyl alcohol?

$1-$chloro$-3-$methylbutane on reaction with zinc and dilute hydrochloric acid gives . . . . . . as the major product.

The reactivity order of the following molecules towards $S_N1$ reaction is:
$(I)$ Allyl chloride
$(II)$ Chlorobenzene
$(III)$ Ethyl chloride

The major product obtained in the following reaction is $C_2H_5ONa + (CH_3)_3C-Cl \rightarrow$

Consider all the structural isomers with molecular formula $C_5H_{11}Br$. They are separately treated with $KOH$ $(aq)$ to give respective substitution products, without any rearrangement. The number of products which can exhibit optical isomerism from these is . . . . . . .

What are reactant $X$ and product $Y$ in the following sequence of reactions?
Reactant $X$ $\xrightarrow{\text{Pyridine, } CH_3C_6H_4SO_2Cl}$ Intermediate $\xrightarrow{NaN_3, \text{Ethanol-water}}$ Product $Y$