Properties of Sulfur Dioxide (SO₂)

Steps:

• Evaluate option A: SO₂ dissolves in water to form sulfurous acid (H₂SO₃), not sulfuric acid (H₂SO₄) used in batteries.
• Evaluate option B: In the Contact process, SO₂ is oxidized to SO₃, which reacts with water to form H₂SO₄ as the final product.
• Evaluate option C: SO₂ acts as an antioxidant and antimicrobial agent in food preservation, such as in dried fruits and wines.
• Eliminate D: SO₂ does not oxidize KI to brown I₂; it reduces I₂ to colorless I⁻, decolorizing solutions.

Why C is correct:

• SO₂ is an E-number additive (E220) approved for food use due to its reducing properties that inhibit microbial growth and oxidation.

Why the others are wrong:

• A: Water + SO₂ yields H₂SO₃, while H₂SO₄ requires further oxidation.
• B: SO₃, not SO₂, is the key intermediate leading to H₂SO₄ in the Contact process.
• D: SO₂ bleaches litmus and reduces halogens but does not produce brown color with KI.

Final answer: C