Pratyush took sulphur powder on spatula and heated it. He collected the gas evolved by inverting a test tube over it as shown below :

(a) What will be the action of gas on

(i) dry litmus paper?

(ii) moist litmus paper?

(b) Write a balanced chemical equation for the reaction taking place.

(a) The gas collected is sulphur dioxide. It is acidic in nature.

(i) No change in colour is seen with dry litmus paper.

(ii) moist blue litmus paper turns red, confirming that the acidic nature of the gas.

(b) S (s) + O₂ (g) ⟶ SO₂ (g)