Which one of the following halogen compounds is not useful as a substrate in an $S_N2$ reaction?

Which among the following is $NOT$ a feature of $S_N1$ mechanisms?

In which of the following compounds,the $C-Cl$ bond ionization shall give the most stable carbocation?

Which reaction is faster $(i)$ or $(ii)$ and what is the mechanism?
$(i) \ CH_3CH_2CH_2Br + CH_3ONa \xrightarrow{DMF} CH_3CH_2CH_2OCH_3 + Br^-$
$(ii) \ CH_3CH_2CH_2Br + CH_3SNa \xrightarrow{DMF} CH_3CH_2CH_2SCH_3 + Br^-$

Given below are two statements:
Statement $I$: $(CH_3)_3C-CH_2-Cl$ will undergo $S_N1$ reaction even though it is a primary halide.
Statement $II$: It will not undergo $S_N2$ reaction very easily even though it is a primary halide.
In the light of the above statements, choose the most appropriate answer from the options given below:

Which of the following is most reactive towards ${S_N}^2$ reaction?