Ammonia liberation from ammonium salt with base

Steps:

• Identify reactants: ammonium sulfate ((NH₄)₂SO₄) provides NH₄⁺ ions; excess NaOH provides OH⁻ ions.
• Note heating condition: promotes reaction where NH₄⁺ acts as acid, reacting with OH⁻ to form NH₃ gas and H₂O.
• Write balanced equation: (NH₄)₂SO₄ + 2NaOH → 2NH₃↑ + Na₂SO₄ + 2H₂O.
• Classify: proton transfer from NH₄⁺ to OH⁻ indicates acid-base neutralization.

Why A is correct:

• NH₄⁺ donates H⁺ to OH⁻, forming NH₃ and H₂O, matching Brønsted-Lowry acid-base definition.

Why the others are wrong:

• B: Products are soluble Na₂SO₄, H₂O, and gaseous NH₃; no solid precipitate.
• C: No electron transfer; N oxidation state stays -3 in NH₄⁺ and NH₃.
• D: Involves chemical reaction with NaOH, not breakdown of single compound by heat alone.

Final answer: A