Neutralization reaction producing only salt and water

Steps:

• Recognize "salt and water only" indicates acid-base neutralization without gases or precipitates.
• Identify acid-base pairs in options: bases react with acids to form salt + H₂O.
• Eliminate reactions producing CO₂, precipitates, or H₂ gas.
• Verify C as the sole acid + alkali pair yielding only salt and water.

Why C is correct:

• Sodium hydroxide (base) + ethanoic acid → sodium ethanoate (salt) + water, per neutralization equation: OH⁻ + H⁺ → H₂O.

Why the others are wrong:

• A: Produces CO₂ gas from carbonate decomposition: Na₂CO₃ + H₂SO₄ → Na₂SO₄ + H₂O + CO₂.
• B: Forms insoluble AgCl precipitate: NaCl + AgNO₃ → AgCl↓ + NaNO₃, no water.
• D: Generates H₂ gas: Zn + 2HCl → ZnCl₂ + H₂.

Final answer: C