Which among the following is a feature of $S_N1$ mechanism?

The transition state of the given $S_N2$ reaction is:

Arrange the compounds of each set in order of reactivity towards $S_{N}2$ displacement:
$(i)$ $2-Bromo-2-methylbutane$,$1-Bromopentane$,$2-Bromopentane$
$(ii)$ $1-Bromo-3-methylbutane$,$2-Bromo-2-methylbutane$,$2-Bromo-3-methylbutane$
$(iii)$ $1-Bromobutane$,$1-Bromo-2,2-dimethylpropane$,$1-Bromo-2-methylbutane$,$1-Bromo-3-methylbutane$.

Which one of the following is the best catalyst for the reaction shown below?
$CH_3(CH_2)_8CH_2Br \xrightarrow[benzene]{KCN} CH_3(CH_2)_8CH_2CN$

Predict the product for the following reaction:
$\xrightarrow[\Delta]{alc. \ KOH}$ product

Identify the product $B$ in the following reaction sequence:
$1$-bromo-$4$-chlorobenzene $\xrightarrow[\text{Dry ether}]{Mg (1 \text{ equivalent})} (A)$ $\xrightarrow{HO-CH_2-CH_2-Cl} (B)$