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?
The major product obtained in the following reaction is :
