Q1. [1] § 2.4 MORE ABOUT SALTS
A metal carbonate reacts with a solution X which forms a salt, water and a gas Y. What are X and Y ?
- (A) X – Sodium hydroxide, Y – Carbon dioxide
- (B) X – Sodium hydroxide, Y – Hydrogen
- (C) X – Hydrochloric acid, Y – Carbon dioxide
- (D) X – Hydrochloric acid, Y – Hydrogen
Previously asked in CBSE board exam
2026 31/2/1 Q18
Generated by claude-sonnet-4-6 · 2026-06-14 10:31 · grounding rag
Model Answer
(C) X – Hydrochloric acid, Y – Carbon dioxide
When a metal carbonate reacts with an acid (HCl), it produces a salt, water, and CO₂ gas. Example: $\text{CaCO}_3 + 2\text{HCl} \rightarrow \text{CaCl}_2 + \text{H}_2\text{O} + \text{CO}_2$
Explanation
- Metal carbonates react with acids, not bases like NaOH — this eliminates options A and B.
- The gas released is always CO₂ (not H₂) when a carbonate reacts with an acid — this eliminates option D.
- Remember the pattern: Carbonate + Acid → Salt + Water + CO₂↑
If a question refers to an image, map, graph or diagram that is not shown here, find the actual CBSE question paper on the CBSE website:
cbse.gov.in.