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.

(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.


Collection of gas - Teachoo.png

(A) When Sulphur is heated, Sulphur dioxide is formed.

  • Sulphur is non-metal , hence its oxide is acidic .


(i)  dry litmus paper

There will be no action of gas on dry litmus paper as both the gas and litmus paper lack moisture.


(ii) moist litmus paper

Sulphur dioxide will react with the moisture to form H 2 SO 4  

  • H 2 SO 4 Is called Sulphuric Acid and is acidic in nature.
  • Hence, it will turn blue litmus red and show no change on red litmus paper.


(B) The chemical equations involved can be written as

Sulphur dioxide turns moist litmus paper Red - Teachoo.png

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Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 14 years and a teacher from the past 18 years. He teaches Science, Economics, Accounting and English at Teachoo