Group 2 Carbonates React with Acids to Evolve CO2

Steps:

• Identify key properties of Group 2 (Mg to Ba) compounds: carbonates decompose thermally but react with acids; nitrates decompose to nitrites; oxides are basic and react with acids without gas.
• Test option A: Carbonates + dilute HNO3 → CO2 gas (bubbles).
• Test options B-D: Check against decomposition or reaction products for inaccuracies.
• Select the option matching standard reactions.

Why A is correct:

• Group 2 carbonates react with dilute nitric acid per MCO₃ + 2HNO₃ → M(NO₃)₂ + H₂O + CO₂↑, producing visible CO₂ bubbles.

Why the others are wrong:

• B: Nitrates decompose to nitrites and oxygen (2M(NO₃)₂ → 2M(NO₂)₂ + O₂), not nitrogen and oxygen.
• C: Oxides react with HCl to form salts and water (MO + 2HCl → MCl₂ + H₂O), producing no gas bubbles.
• D: Group 2 oxides are basic, reacting with acids but not with bases (amphoteric applies to elements like Al).

Final answer: A