Question

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

1. What will be the action of gas on
   (i) dry litmus paper?
   (ii) moist litmus paper?
2. Write a balanced chemical equation for the reaction taking place.
   

Answer 1

(a) (i) There will be no action on dry litmus paper.
(ii) Since the gas is sulphur dioxide $(SO_2)$, it turns moist blue litmus paper to red because sulphur dioxide reacts with moisture to form sulphurous acid.

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(b) $S(s) + O_2(g) → SO_2(g)$
(Sulphur dioxide)