Presence of halogen in organic compounds can be detected using

Lassaigne's test is used for the detection of:

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

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?

Which test is useful for the detection of halogens in organic compounds?