Which of the following alkyl halides undergoes a substitution reaction according to the $S_{N}1$ mechanism?

$S_{N}1$ and $S_{N}2$ products are the same (excluding stereoisomers) for which of the following compounds?

The major product of the following reaction is:

Most reactive compound toward $S_N1$ is

Identify the product obtained when $2$-chlorobutane is heated with an aqueous solution of potassium hydroxide.

For each of the following pairs of $E_2$ reactions,select the one that occurs with the greater rate constant:
$(1)$ $CH_3-CH_2-CH_2-Cl + CH_3-C(CH_3)_2-O^-$
$(2)$ $CH_3-CH_2-CH_2-I + CH_3-C(CH_3)_2-O^-$
$(3)$ $CH_3-CH(Br)-CH_3 + CH_3-O^-$
$(4)$ $CH_3-CH(Br)-CH_3 + CH_3-S^-$
$(5)$ $Ph-CH_2-CH(Br)-CH_2-CH_3 + OH^-$
$(6)$ $Ph-CH_2-CH_2-CH(Br)-CH_3 + OH^-$