The product obtained by the nitration of nitrobenzene is.....

$\text{Benzene} + Cl_2$ $\xrightarrow{FeCl_3} X$ $\xrightarrow{R-X, \text{ Na/dry ether }} Y$
Conversion of $X$ to $Y$ is an example of:

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.

Aryl halides are extremely less reactive towards nucleophilic substitution. Predict and explain the order of reactivity of the following compounds towards nucleophilic substitution:
$(I)$ $p$-nitrochlorobenzene
$(II)$ $2,4$-dinitrochlorobenzene
$(III)$ $2,4,6$-trinitrochlorobenzene

$DDT$ can be prepared by reacting chlorobenzene (in the presence of conc. $H_2SO_4$) with

The compound that reacts the fastest with sodium methoxide is