The product$(s)$ formed when toluene is reacted with $Cl_2$ in the presence of $Fe$ in the dark is/are:

Which of the following is least reactive towards $S_{N}1$ reaction?

The lower reactivity of the chlorine atom in $CH_2 = CH - Cl$ is due to:

Assertion : $S_{N}2$ reaction of an optically active aryl halide with an aqueous solution of $KOH$ always gives an alcohol with opposite sign of rotation.
Reason : $S_{N}2$ reactions always proceed with retention of configuration.

The compounds $P$,$Q$,and $S$ were separately subjected to nitration using $HNO_3 / H_2SO_4$ mixture. The major product formed in each case respectively,is

Reaction of aqueous sodium hydroxide on $(i)$ ethyl bromide and $(ii)$ chlorobenzene gives: