Thermal decomposition of strontium nitrate

Steps:

• Identify the compound as a Group 2 nitrate, which decomposes on strong heating.
• Write the balanced equation: 2Sr(NO3)2 → 2SrO + 4NO2 + O2.
• Note products: brown NO2 gas, O2 gas, white SrO solid.
• Match products to statements for correctness.

Why A is correct:

• Nitrogen dioxide (NO2) from the decomposition is a brown gas, as per the reaction equation.

Why the others are wrong:

• B: The primary gas is NO2, which extinguishes a glowing splint; O2 amount is minor and not the focus.
• C: Strong heating leaves white SrO, but statement implies no change, which is inaccurate.
• D: Not enough information.

Final answer: A