Given below are two statements: Statement-I: The gas liberated on warming a salt with dil H 2 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:

Step-by-step solution

With warm dilute H 2 SO 4 a sulphide gives hydrogen sulphide gas which smells like rotten eggs. A piece of filter paper dipped in lead acetate solution turns black on exposure to the gas due to the formation of lead sulphide which is black in colour. As we know, hydrogen sulphide gas is a colourless gas and when it reacts with lead acetate it produces lead sulphide and acetic acid. The chemical reaction of hydrogen sulphide with lead acetate is given as: Na 2 S + H 2 SO 4 → Na 2 SO 4 + H 2 S CH 3 COO 2 Pb + H 2 S →