Match column $-I$ and column $-II$ with the correct relation:

Column $-I$	Column $-II$
$(i).$ Prussian blue	$(a).$ Presence of phosphorus
$(ii).$ Yellow precipitate	$(b).$ Presence of sulphur
$(iii).$ Purple solution	$(c).$ Presence of nitrogen
$(iv).$ Black precipitate	$(d).$ Presence of chlorine

In the Lassaigne's test for nitrogen in an organic compound,the Prussian blue colour is obtained due to the formation of:

Three students,Manish,Ramesh,and Rajni were determining the extra elements present in an organic compound given by their teacher. They prepared the Lassaigne's extract $(L.E.)$ independently by the fusion of the compound with sodium metal. Then they added solid $FeSO_4$ and dilute sulphuric acid to a part of the Lassaigne's extract. Manish and Rajni obtained prussian blue colour,but Ramesh got red colour.
Ramesh repeated the test with the same Lassaigne's extract,but again got red colour only. They were surprised and went to their teacher and told him about their observation. Teacher asked them to think over the reason for this. Can you help them by giving the reason for this observation? Also,write the chemical equations to explain the formation of compounds of different colours.

The compound formed in the positive test for nitrogen with the Lassaigne solution of an organic compound is

Which one of the following sets of elements can be detected using sodium fusion extract?

The compound that does not give a positive test for nitrogen in Lassaigne's test is