Question

In sodium extract nitrogen is present as:

• A. Sodamide
• B. Sodium cyanide
• C. Sodium nitrite
• D. Sodium nitrate

Answer 1

The correct option is B Sodium cyanide

Lassaigne's test is a general test for the detection of halogens, nitrogen and sulphur in an organic compound. These elements are covalently bonded to the organic compounds. In order to detect them, they have to be converted into their ionic forms. This is done by fusing the organic compound with sodium metal. The ionic compounds formed during the fusion are extracted in aqueous solution. Nitrogen containing organic compounds fuse with Na and form NaCN which is used for detection of nitrogen.
$Na+C+N\stackrel{△}{\to }NaCN$