Among the following compounds,which one has the shortest $C-Cl$ bond?

Which alkyl halide from the following pairs would you expect to react more rapidly by an $S_N2$ mechanism? Explain your answer.
$(i)$ $CH_3CH_2CH_2CH_2Br$ or $CH_3CH_2CH(Br)CH_3$
$(ii)$ $CH_3CH_2CH(Br)CH_3$ or $(CH_3)_3CBr$
$(iii)$ $CH_3CH(CH_3)CH_2CH_2Br$ or $CH_3CH_2CH(CH_3)CH_2Br$

Which of the following haloalkanes is most reactive towards nucleophilic substitution reactions?

Which of the following alkyl halides is most reactive towards the $S_{N}1$ mechanism?

Which of the following reactants is used to obtain the compound $(A)$ shown below? (Assume that $EtO^{-}$ is used in all the reactions)

Ethylene dichloride $(ClCH_2-CH_2Cl)$ and ethylidene chloride $(CH_3-CHCl_2)$ are isomeric compounds. Identify the statement which is not applicable to both of them.