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 $Y$

Consider the following reaction,
$C_2H_5Cl + AgCN \xrightarrow{EtOH / H_2O} \underline{X} \text{ (major)}$
Which one of the following statements is true for $\underline{X}$?
$(I)$ It gives propionic acid on hydrolysis
$(II)$ It has an ester functional group
$(III)$ It has a nitrogen linked to ethyl carbon
$(IV)$ It has a cyanide group

Identify the major product formed in the following reaction: $3-$Bromo$-2-$methylpentane $\xrightarrow{Alc. KOH, \Delta}$ Major product

What is the correct order of reactivity of halides for the $S_{N}2$ reaction?

Most reactive compound toward $S_N1$ is

Identify compound $Y$ in the following reaction.
$C_2H_5Cl + Y \xrightarrow{\Delta} C_2H_5CN$