Which of the following undergoes nucleophilic substitution by $S_N1$ mechanism?

The hydrolysis of $2$-bromo-$3$-methylbutane by the $S_N1$ mechanism primarily yields:

Compare the rate of reaction with $AgNO_3$ for the following compounds:

Which of the following compounds has a chiral carbon atom?

Given below are two statements:
Statement $(I)$: Benzyl chloride reacts faster in $S_N1$ mechanism than ethyl chloride.
Statement $(II)$: Ethyl carbocation intermediate is less stabilized by hyperconjugation than benzyl carbocation by resonance.
In the light of the above statements, choose the correct answer from the options given below:

Arrange the following in the correct order of reactivity towards $S_{N}2$ reaction:
$I$: $1$-Chloropropane
$II$: $2$-Chloropropane
$III$: $1$-Iodopropane
$IV$: $2$-Iodopropane