In the given reaction sequence,$(X)$ and $(Y)$ are:

Match the reactions given in Column-$I$ with their names given in Column-$II$.

Column-$I$	Column-$II$
$(i)$ $R-Cl + NaI \xrightarrow{\text{dry acetone}} R-I + NaCl$	$(a)$ Swarts reaction
$(ii)$ $CH_3-Br + AgF \xrightarrow{\Delta} CH_3-F + AgBr$	$(b)$ Wurtz reaction
$(iii)$ $R-X + Mg$ $\xrightarrow{\text{dry ether}} R-Mg-X$ $\xrightarrow{H_2O} RH + Mg(OH)X$	$(c)$ Finkelstein reaction
	$(d)$ Grignard reaction

Identify product $A$ in the following reaction:
$4-methylcyclohexyl bromide + OH^- \xrightarrow{S_N2} A$

The order of reactivity of the given haloalkanes towards nucleophiles is:

Some alkyl halides undergo substitution whereas some undergo elimination reaction on treatment with bases. Discuss the structural features of alkyl halides with the help of examples which are responsible for this difference.

The major product '$B$' in the below mentioned reaction is:
$CH_3-CH(Br)-CH_3 \xrightarrow[\Delta]{\text{Alc. KOH}} A \xrightarrow[\text{Peroxide absent}]{\text{HBr}} B$