Lassaigne's test for the detection of nitrogen fails in

Match Column $-I$ with Column $-II$.

Column $-I$	Column $-II$
$(A).$ Dumas method	$(3).$ Nitrogen gas
$(B).$ Kjeldahl's method	$(5).$ Ammonium sulphate
$(C).$ Carius method	$(1).$ $AgNO_3$
$(D).$ Chromatography	$(2).$ Silica gel
$(E).$ Homolytic fission	$(4).$ Free radical

Explain the reason for the fusion of an organic compound with metallic sodium for testing nitrogen,sulphur,and halogens.

Sodium fusion extract of aniline,when heated with ferrous sulphate solution and then acidified with concentrated $H_2SO_4$,forms which of the following complexes?

For testing halogens in an organic compound with $AgNO_{3}$ solution,sodium extract (Lassaigne's test) is acidified with dilute $HNO_{3}$. What will happen if a student acidifies the extract with dilute $H_{2}SO_{4}$ in place of dilute $HNO_{3}$?

In Lassaigne's extract of an organic compound,both nitrogen and sulphur are present,which gives blood red colour with $Fe^{3+}$ due to the formation of-