SO₂ forms sulfite with Ca(OH)₂

Steps:

• Write the balanced equation: SO₂ + Ca(OH)₂ → CaSO₃ + H₂O.
• Identify the initial product as calcium sulfite (CaSO₃) from the direct reaction.
• Confirm aqueous conditions favor sulfite formation without oxidation.
• Rule out further products like sulfate, as the question asks for the first formed.

Why C is correct:

• SO₂ acts as an acidic oxide, reacting with base Ca(OH)₂ to form the sulfite salt CaSO₃ per acid-base neutralization.

Why the others are wrong:

• A: Ca(HSO₃)₂ forms only with excess SO₂, not the main initial product.
• B: CaS requires reduction of SO₂ to sulfide, which does not occur here.
• D: CaSO₄ results from SO₂ oxidation to SO₄²⁻, not the first step.

Final answer: C