Arrange the following three chlorides in decreasing order of their reactivity towards $S_{N^1}$ reaction.

The ease of dehydrohalogenation of alkyl halide with alcoholic $KOH$ is:

Predict the order of reactivity of the following compounds in $S_{N}1$ and $S_{N}2$ reactions:
$(i)$ The four isomeric bromobutanes
$(ii)$ $C_{6}H_{5}CH_{2}Br$,$C_{6}H_{5}CH(C_{6}H_{5})Br$,$C_{6}H_{5}CH(CH_{3})Br$,$C_{6}H_{5}C(CH_{3})(C_{6}H_{5})Br$

The major product obtained in the following reaction is:

Which of the following $S_N2$ reactions is the slowest?

In the following pairs of halogen compounds,which compound undergoes faster $S_N1$ reaction?
$(i)$ $2$-chloro-$2$-methylpropane and $3$-chloropentane
(ii) $2$-chloroheptane and $1$-chlorohexane