Which compound might be synthesized by the $S_N2$ displacement of an alkyl-halide?

Among the following chlorides, the compounds which will be hydrolysed most easily and most slowly in aqueous $NaOH$ solution are respectively:
$1$. Methoxymethyl chloride $(CH_3OCH_2Cl)$
$2$. Benzyl chloride $(C_6H_5CH_2Cl)$
$3$. Neopentyl chloride $((CH_3)_3CCH_2Cl)$
$4$. Propyl chloride $(CH_3CH_2CH_2Cl)$

The organic halide,which does not undergo hydrolysis by $S_{N}1$ mechanism is

Which of the following factors favors an $S_N1$ reaction?

Reaction of $t-$butyl bromide with sodium methoxide produces

What happens when $CCl_4$ is treated with $AgNO_3$?