Vinyl chloride reacts with $HCl$ to form

The reactivity of alkyl bromides towards iodide ion in dry acetone decreases in the order:
$I. CH_3CH_2Br$
$II. CH_3-CH(CH_3)-Br$
$III. CH_3-C(CH_3)_2-Br$
$IV. CH_3Br$

Which one of the following compounds is inactive towards $S_N1$ reaction?

The reaction of $CH_3CD_2CHBr-CH_2CD_3$ with alc. $KOH$ yields:

Identify the most suitable reagents $(I)$ and $(II)$ for the following sequence of reactions:

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