CBSE Class 10 Science 2019 · Paper 31/1/1/C · Question 22(b)

Chemical Reactions and Equations 2 marks Medium

State the observation and inference made by a student when he brings

(i)a wet blue litmus paper and
(ii)a wet red litmus paper in contact with the gas liberated during thermal decomposition of ferrous sulphate.

Answer

Wet blue litmus turns red and wet red litmus is unchanged, so the gases, $SO_{2}$ and $SO_{3}$ , are acidic.

On heating, ferrous sulphate decomposes:

2 FeSO_{4} \to Fe_{2} O_{3} + SO_{2} + SO_{3}

. (i) Observation: the wet blue litmus paper turns red. (ii) Observation: the wet red litmus paper shows no change; it stays red. Inference: the gases liberated, sulphur dioxide and sulphur trioxide, are acidic in nature - they dissolve in the water on the wet paper to form acids.

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CBSE Class 10 Science 2019 · Paper 31/1/1/C · Question 22(b)

Answer

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