• question_answer Lassaigne's test for the detection of nitrogen fails in A)  ${{H}_{2}}N-CO-NHN{{H}_{2}}.HCl$B)  $N{{H}_{2}}-N{{H}_{2}}.HCl$C)  $N{{H}_{2}}-CO-N{{H}_{2}}$D)  ${{C}_{6}}{{H}_{5}}CON{{H}_{2}}$

Lassaigne's test is given by those nitrogenous compound in which carbon is also present along with nitrogen, (organic compound only). In $N{{H}_{2}}.N{{H}_{2}}.HCl$ carbon is absent so it does not give Lassaigne's test.