Which of the following compounds is most reactive towards $S_N1$ reaction?

The correct sequence of reagents for the conversion of $X$ to $Y$ is :

Among the bromides $(I)-(III)$ given below,the order of reactivity for ${S_N}^1$ reaction is:

Assertion $A:$ Hydrolysis of an alkyl chloride is a slow reaction but in the presence of $NaI$,the rate of the hydrolysis increases.
Reason $R:$ $I^{-}$ is a good nucleophile as well as a good leaving group.
In the light of the above statements,choose the correct answer from the options given below.

The configurations of the reactant and the product in the following reaction,respectively,are:

Which of the following chloro compounds has a dipole moment?