Question

Lassaigne’s test is used for the detection of which of the following element(s):

• A. Nitrogen
• B. Sulphur
• C. Chlorine
• D. Oxygen

Answer 1

Answer: (A), (B), (C)

Chlorine

Lassaigne’s test can be carried out with the help of sodium fusion extract.
In this test, the elements present in a compound are converted from covalent to ionic form by fusing the organic compound with Sodium (Na) metal because ionic forms are more reactive.
$Na+C+N\stackrel{\Delta }{⟶}NaCN2Na+S\stackrel{\Delta }{⟶}N{a}_{2}SNa+X\stackrel{\Delta }{⟶}NaX$

Cyanides, sulphides and halides of sodium formed on sodium fusion are extracted from the fused mass by boiling with water.
This extract is known as Sodium Fusion Extract (Lassaigne Extract).
These extracts can be used for the detection of nitrogen, sulphur and halogens by running simple chemical test.
Thus, the correct options are (a), (b) and (c).