Which of the following compounds has the fastest $S_N2$ reaction rate?

Which among the following is $NOT$ a correct statement about $S_{N}1$ reaction?

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 of the following compounds would undergo $S_N1$ reaction faster and why?
$(A)$ Cyclohexylmethyl chloride
$(B)$ Benzyl chloride

The major product of the following reaction is:

From the given pairs of compounds,in which will the first compound undergo $S_N2$ reaction faster?