Account for the following
Although, amino group is o-and p-directing in aromatic electrophilic substitution reactions, aniline on nitration gives a substantial amount of m-nitroaniline.

Explanation

Nitration is usually carried out with a mixture of conc. `HNO_(3)` and conc. `H_(2)SO_(4)`. So, in the presence of these acids, aniline gets protonated to form anilinium ion. Therefore, in the presence of these acids, the reaction mixture consists of aniline and anilinium ion. `-NH_(2)` group in aniline is o, p-directing and activating, whereas, the `overset(+)(N)H_(3)` group in anilinium ions is m-directing and deactivating. Now, nitration of aniline mainly gives p-nitroaniline due to steric hindrance at o-position, the nitration of anilinium ion gives m-nitroaniline. In actual practice approx `1:1` mixture of p-nitroaniline and m-nitroaniline is obtained