Starting from aniline how can the following be prepared ?
(a) Chloro benzene
(b) p-hydroxy azobenzene
(c) Benzonitrile
(d) p-amino azo benzene

Explanation

(a) `C_(6)H_(5)NH_(2) overset(HNO_(2))underset(HCl)rarr C_(6)H_(5)N_(2)Cl overset(HCl)underset(Cu_(2)Cl_(2))rarr C_(6)H_(5)Cl`
(b) `C_(6)H_(5)NH_(2) overset(HNO_(2))underset(HCl)rarr C_(5)H_(5)N_(2)Cl overset("Phenol")rarr C_(6)H_(5)-N=N-C_(6)H_(4)-OH`
(c ) `C_(6)H_(5)NH_(2) overset (HNO_(2))underset(HCl)rarr C_(6)H_(5)N_(2)Cl overset(KCN) underset(Cu_(2)(CN)_(2))rarr C_(6)H_(5)CN`
(d) `C_(6)H_(5)NH_(2) overset (HNO_(2)) underset(HCl)rarr C_(6)H_(5)N_(2)Cl overset("Aniline")rarr C_(6)H_(5)N=NC_(6)H_(4)NH_(2)`