Explain the nitration and sulphonation of aniline.

(N/A) Nitration: Direct nitration of aniline with concentrated $HNO_3$ and $H_2SO_4$ at $288 \ K$ yields a mixture of $p$-nitroaniline $(51\%)$,$m$-nitroaniline $(47\%)$,and $o$-nitroaniline $(2\%)$. The formation of the $m$-derivative is due to the protonation of the $-NH_2$ group in the strongly acidic medium to form the anilinium ion,which is meta-directing. To obtain $p$-nitroaniline as the major product,the $-NH_2$ group is protected by acetylation with acetic anhydride to form acetanilide,which is then nitrated and subsequently hydrolyzed.
Sulphonation: Aniline reacts with concentrated sulphuric acid to form anilinium hydrogensulphate. Upon heating this salt with sulphuric acid at $453-473 \ K$,it undergoes rearrangement to produce $p$-aminobenzene sulphonic acid,commonly known as sulphanilic acid,as the major product. This exists as a zwitter ion.