Question

Which of the following compound will give blood red colour while doing the Lassigne's test for N?

Answer 1

H2N(C6H4)SO3HH2N(C6H4)SO3H  contains N, S and C. During fusion with sodium metal, it will form

NaCNSNaCNS which gives a blood red colouration with Fe3+Fe3+ions.

Na+N+C+S−→−−FuseNa+CNS−Na+N+C+S→FuseNa+CNS−

Fe3++3CNS−⟶Fe(CNS)3Fe3++3CNS−⟶Fe(CNS)3 Ferric sulphocyanide (Blood red colouration)

hope it helps...