Carbonate reaction with dilute sulfuric acid produces CO₂ and sulfate precipitate Steps:

• Colorless gas indicates CO₂ from acid reacting with carbonate solid X.
• White precipitate forms as insoluble sulfate from cation of X and anion of acid Y.
• Excess Y ensures complete reaction of X, with precipitate distinct from original X.
• Evaluate options: Only CaCO₃ + dil. H₂SO₄ yields observable CO₂ effervescence and CaSO₄ precipitate. Why B is correct:
• CaCO₃(s) + H₂SO₄(aq) → CaSO₄(s)↓ (white ppt) + CO₂(g) + H₂O(l); CaSO₄ is new product, not X. Why the others are wrong:
• A: BaSO₄ highly insoluble, coats BaCO₃ limiting CO₂ evolution.
• C: Forms soluble MgSO₄, no precipitate.
• D: No reaction; SiO₂ remains undissolved, no gas.

Final answer: B