Question

Which of the following compound is added to the Sodium extract before the addition of Silver nitrate for testing of halogens?

• A. Nitric acid
• B. Sodium hydroxide
• C. Hydrochloric acid
• D. Ammonia

Answer 1

The correct option is A

Nitric acid

The explanation for the correct option: A

1. The sodium fusion test or the Lassaigne's test is used for the qualitative test of elements like Nitrogen(N), Sulphur(S) and halogens.
2. For this test, we make an extract by fusing sodium metal in the presence of heat.
3. In the test of halogens, this extract is acidified with Nitric acid(${\mathrm{HNO}}_3$) and is then treated with Silver nitrate(${\mathrm{AgNO}}_3$).
4. Nitric acid helps in decomposing $\mathrm{NaCN}\mathrm{and}{\mathrm{Na}}_2\mathrm{S}$in the form of $\mathrm{HCN}\mathrm{and}{\mathrm{H}}_2\mathrm{S}$ else they interupt in the reaction.
5. Hence the correct option is A.