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

Given below are two statements:
Statement $I$ : Sulphanilic acid gives esterification test for carboxyl group.
Statement $II$ : Sulphanilic acid gives red colour in Lassaigne's test for extra element detection.
In the light of the above statements,choose the most appropriate answer from the options given below :

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

Lassaigne's test is used for the detection of:

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:

Lassaigne's test is not used for the detection of which element?