The major product formed when $1$-Bromo-$3$-chlorocyclobutane reacts with metallic sodium in dry ether is

$2-$chloro$-2-$methylpentane on reaction with sodium methoxide in methanol yields:
$(1)\ C_2H_5-CH_2-C(CH_3)_2-OCH_3$
$(2)\ C_2H_5-CH_2-C(CH_3)=CH_2$
$(3)\ C_2H_5-CH=C(CH_3)_2$

Match the following reactants with their corresponding products:
Reactants:
$(A)$ $C_2H_5Cl$,moist $Ag_2O$
$(B)$ $C_2H_5Cl$,ethanolic $AgCN$
$(C)$ $C_2H_5Cl$,ethanolic $AgNO_2$
$(D)$ $C_2H_5Cl$,ethanolic $KOH$
Products:
$(i)$ $CH_3CH_2ONO$
$(ii)$ $C_2H_4$
$(iii)$ $CH_3CH_2OH$
$(iv)$ $CH_3CH_2NC$
Select the correct match:

Which is most reactive for $S_{N}2$ reaction?

Select the reagent that will yield the greater amount of substitution on reaction with $CH_3CH_2Br$.

Which of the following is most reactive for $S_{N}1$ reaction?