KI in acetone, undergoes ${\mathrm{S}}_{\mathrm{N}}2$ reaction with each of P, Q, R and S. The rates of the reaction vary as

The major product of the following reaction is:

The reagent required for the following two step transformation are

The increasing order of reactivity of the following compounds towards reaction with alkyl halides directly is:

$\left(i\right)$

$\left(ii\right)$

$\left(iii\right)$

$\left(iv\right)$

The major product of the following reaction is:

The major product of the following reaction is: