Thermal decomposition of calcium nitrate yields two gases

Steps:

• Identify reactions: Examine each option for gaseous products from calcium compounds.
• Analyze A: Ca(NO3)2 decomposes on heating to CaO + 2NO2 + 1/2 O2, producing NO2 and O2.
• Analyze B: CaCO3 decomposes to CaO + CO2, producing only CO2.
• Analyze C: Ca + 2H2O → Ca(OH)2 + H2, producing only H2.
• Analyze D: CaCO3 is insoluble in water, no reaction or gases.

Why A is correct:

• Decomposition follows 2Ca(NO3)2 → 2CaO + 4NO2 + O2, releasing two distinct gases (NO2, O2).

Why the others are wrong:

• B: Only one gas (CO2) from thermal decomposition.
• C: Only one gas (H2) from metal-water reaction.
• D: No reaction occurs, so no gases produced.

Final answer: A