Chemistry · Oct / Nov 2025 · Paper 11 · Question 39

Sulfur dioxide is a gas that is prepared by heating sodium sulfite with hydrochloric acid. It is an acidic gas. Sulfur dioxide is more dense than air. Which set of apparatus is suitable for preparing and collecting a dry sample of sulfur dioxide?

1. Asodium sulfite + hydrochloric acid, heat; concentrated sulfuric acid drying tube; gas collected by downward delivery
2. Bsodium sulfite + hydrochloric acid, heat; concentrated sulfuric acid drying tube; gas collected over water
3. Csodium sulfite + hydrochloric acid, heat; calcium oxide drying tube; gas collected by downward delivery
4. Dsodium sulfite + hydrochloric acid, heat; concentrated sulfuric acid drying tube; gas collected by upward delivery

As printed in the paper