Primary amine groups when reacts with NaNO2/HCl or HNO2 at 0oC, it undergoes diazotisation and forms diazonium salt (−N=N−). So, the compound X will be C6H5N=N−Cl Benzene diazonium chloride) When benzene diazonium chloride reacts with HNO2 in presence of HCHO nitrobenzene is obtained. The reactions are as under: C6H5NH2NaNO2/HCl0−5oCBenzenediazoniumchlorideC6H5N=NClHNO2CH2OC6H5NO2+N2+HCl