Arrange the following compounds in the decreasing order of reactivity towards electrophilic substitution reaction.

(I) Chlorobenzene

(II) Nitrobenzene

(III) Benzene

(IV) Isopropylbenzene

Arrange the following in the order of increasing reactivity towards $$\mathrm{SN}_{\mathrm{2}}$$ reactions.

$$\begin{array}{ll} \left(\mathrm{CH}_3\right)_3 \mathrm{CCH}_2 \mathrm{Br}(\mathrm{P}) ; & \\\mathrm{CH}_3\left(\mathrm{CH}_2\right)_3 \mathrm{Br}(\mathrm{Q}) ; &\\ \mathrm{CH}_3 \mathrm{CH}_2-\mathrm{CH}\left(\mathrm{CH}_3\right)-\mathrm{CH}_2 \mathrm{Br}(\mathrm{R}) ; & \\\left(\mathrm{CH}_3\right)_2 \mathrm{CHCH}_2 \mathrm{CH}_2 \mathrm{Br}(\mathrm{S}) \end{array}$$

Choose the incorrect statement from the following.

Consider the following reaction

$$(\mathrm{CH}_3)_2 \mathrm{CHCH}_2 \mathrm{Br}+(\mathrm{CH}_3)_3 \mathrm{CCH}_2 \mathrm{Br} \xrightarrow[\Delta]{\mathrm{Na} \text { /dry ether }} \mathrm{X}+\mathrm{Y}+\mathrm{Z}$$

Identify the product which is not formed?