Ethylene difluoride on hydrolysis gives

For the reaction of $3$-bromohexane with alcoholic $KOH$,find $(x)$,where $(x)$ is the total number of $E_2$ elimination products obtained (including stereoisomers).

The reagents required for the following two-step transformation are:

For the reaction:
$RCH_2Br + I^{-} \stackrel{\text{Acetone}}{\longrightarrow} RCH_2I + Br^{-}$
The correct statement is:

Compare the rate of $E_2$ reaction for the following compounds:
$a$: $(CH_3)_3C-Br$
$b$: $CH_3-CH(Br)-CH_3$
$c$: $CH_3-CH_2-Br$

$CH_3CH_2CH_2OH$ $\xrightarrow{PCl_5} A$ $\xrightarrow{\text{alcoholic } KOH} B$. The final product $B$ is ...... .