Question

The Lassaigne's extract is boiled with conc. HNO₃ while testing for halogens. By doing so it

(a) decomposes Na₂S and NaCN, formed

(b) helps in the precipitation of AgCl

(c) increases the solubility product of AgCl

(d) increases the concentration of NO₃^- ions

Answer 1

The correct option is: (a) decomposes Na₂S and NaCN, formed

Explanation: 

In case of Lassaigne's test of halogens, it is necessary to remove sodium cyanide and sodium sulphide from the sodium extract if nitrogen and sulphur are present. This is done by boiling the sodium extract with conc. HNO₃.