Which of the products indicates the presence of sulphur atom in an organic compound,in qualitative elemental analysis?

Nitrogen detection in an organic compound is carried out by Lassaigne's test. The blue colour formed corresponds to which of the following formulae?

The violet color obtained in the Lassaigne's test for a sulfur-containing compound is due to the formation of which species?

Presence of halogen in organic compounds can be detected using

Lassaigne’s test is used to detect which of the following elements in an organic compound?

An organic compound $A$ is oxidized with $Na_2O_2$ followed by boiling with $HNO_3$. The resultant solution is then treated with ammonium molybdate to yield a yellow precipitate. Based on the above observation,the element present in the given compound is: