Which of the following would not give $2-$phenylbutane as the major product in a Friedel-Crafts alkylation reaction?

In the $S_{N}2$ substitution reaction $R-Br + Cl^- \xrightarrow{DMF} R-Cl + Br^-$,which of the following will have the highest rate?

For the following compounds,the correct statement$(s)$ with respect to nucleophilic substitution reactions is(are):
$I$: Benzyl bromide $(C_6H_5CH_2Br)$
$II$: Cyclohexylmethyl bromide $(C_6H_{11}CH_2Br)$
$III$: tert-Butyl bromide $((CH_3)_3CBr)$
$IV$: $1-$Phenylethyl bromide $(C_6H_5CH(CH_3)Br)$
$A$. $I$ and $III$ follow $S_{N}1$ mechanism
$B$. $I$ and $II$ follow $S_{N}2$ mechanism
$C$. Compound $IV$ undergoes inversion of configuration
$D$. The order of reactivity for $I$,$III$ and $IV$ is: $IV > I > III$

The reactivity of $2-$bromo$-2-$methylbutane $(I)$,$1-$bromopentane $(II)$ and $2-$bromopentane $(III)$ towards $S_N2$ displacement is such that :

For the following reaction,the yield of the product is highest in:
$CH_3-Br + NaOH \to CH_3-OH + NaBr$

What is the product formed when $CH_3-CH=CHBr$ reacts with $HBr$ in the presence of peroxide?