How will you detect the presence of chlorine in an organic compound using Lassaigne's test?

How will you detect the presence of unsaturation in an organic compound?

How can you detect the presence of nitrogen in an organic compound?

How is sodium fusion extract prepared? Using this, how will you detect the presence of Nitrogen, Sulphur and Halogen in an organic compound?

Write the chemical equations involved in the detection of N, halogen and sulphur present in an organic compound by Lassaigne's test.

How is the presence of SO_2 detected?