Thermal decomposition of Group 2 nitrates produces O₂ and NO₂

Steps:

• Glowing splint relights only with oxygen gas, identifying one product.
• Mixture decomposes to white solid and exactly two gases total.
• Group 2 nitrates follow 2M(NO₃)₂ → 2MO (white solid) + 4NO₂ + O₂.
• Mg(NO₃)₂ and Ca(NO₃)₂ mixture yields white MgO/CaO solids and NO₂/O₂ gases.

Why C is correct:

• Decomposition equation 2M(NO₃)₂ → 2MO + 4NO₂ + O₂ produces white oxide, brown NO₂ gas, and O₂ that relights splint.

Why the others are wrong:

• A: Group 2 chlorides are thermally stable and produce no O₂ or two gases.
• B: Carbonates decompose to MO + CO₂ (one gas); CO₂ extinguishes splint.
• D: Oxides do not decompose thermally to any gases.

Final answer: C