When ${\mathrm{H}}_2\mathrm{S}$ gas is bubbled through an aqueous solution of Copper(II) sulphate, a black precipitate of $\mathrm{CuS}$ is obtained. Write a balance reaction.

Q. When hydrogen sulphide gas is passed through a blue solution of copper sulphate, a black precipitate of copper sulphide is obtained and the sulphuric acid so formed remains in the solution. The reaction is an example of:

Q. A red-brown metal X forms a salt XSO₄. When hydrogen sulphide gas is passed through an aqueous solution of XSO₄, then a black precipitate of XS is formed alongwith sulphuric acid solution.
(a) What could the salt XSO₄ be?
(b) What is the colour of salt XSO₄?
(c) Name the black precipitate XS.
(d) By using the formula of the salt obtained in (a) above, write an equation of the reaction which takes place when hydrogen sulphide gas is passed through its aqueous solution.
(e) What type of chemical reaction takes place in this case?

Q.

A red-brown metal X forms a salt $XS{O}_4$. When hydrogen sulphide gas is passed through an aqueous solution of $XS{O}_4$, then a black precipitate of XS is formed alongwith sulphuric acid solution.

(a) What could the salt $XS{O}_4$ be ?

(b) What is the colous of salt $XS{O}_4$ ?

(c) Name the black precipitate XS.

(d) By using the formula of the salt obtained in (a) above, write an equation of the reaction which takes place when hydrogen sulphide gas is passed through its aqueous solution.

(e) What type of chemical reacion takes place in this case ?

Q. When aqueous $KCN$ is added to a solution of copper(II) sulphate, a white precipitate, soluble in an excess of $KCN$ is formed. No precipitate is formed when $H_{2}S$ is passed into it.

Q. An aqueous solution of a gas (X) shows the following reactions :
(i) It turns red litmus blue
(ii) When added in excess to a copper sulphate solution, a deep blue colour is obtained.
(iii) On addition to a ferric chloride solution, a brown precipitate, soluble in dilute nitric acid, is obtained.