Given below are two statements :

Statement (I) : The gas liberated on warming a salt with dil $$\mathrm{H}_2 \mathrm{SO}_4$$, turns a piece of paper dipped in lead acetate into black, it is a confirmatory test for sulphide ion.

Statement (II) : In statement-I the colour of paper turns black because of formation of lead sulphite. In the light of the above statements, choose the most appropriate answer from the options given below :

The Lassiagne's extract is boiled with dil $$\mathrm{HNO}_3$$ before testing for halogens because,

On passing a gas, '$$\mathrm{X}$$', through Nessler's regent, a brown precipitate is obtained. The gas '$$\mathrm{X}$$' is

Identify the incorrect pair from the following :