Industrial uses of SO₂ and H₂SO₄

Steps:

• Identify key uses: SO₂ bleaches by reducing colored compounds; H₂SO₄ serves as battery electrolyte.
• Evaluate A: Matches SO₂ bleaching and H₂SO₄ in batteries.
• Check B–D: Eliminate mismatches like SO₂ in food preservation or fertilizers, and H₂SO₄ as bleach.
• Confirm A as only fully accurate pair.

Why A is correct:

• SO₂ bleaches via reduction (e.g., SO₂ → SO₄²⁻ + 2H⁺ + 2e⁻); H₂SO₄ dissociates to H⁺ and SO₄²⁻ for battery conduction.

Why the others are wrong:

• B: H₂SO₄ corrodes, not bleaches.
• C: SO₂ unrelated to detergents; H₂SO₄ not a bleach.
• D: SO₂ not used in fertilizers; H₂SO₄ is, but pair inaccurate.

Final answer: A