Chlorine-Hydrogen Explosive Reaction

Steps:

• Evaluate A: Iodine acts as an oxidizing agent, e.g., in iodometric titrations.
• Evaluate B: Volatility decreases down the group due to increasing molecular mass and London forces.
• Evaluate C: Cl₂ + H₂ → 2HCl is a complete, explosive reaction yielding only HCl.
• Select C as the sole correct statement.

Why C is correct:

• The reaction follows the balanced equation Cl₂(g) + H₂(g) → 2HCl(g), producing exclusively hydrogen chloride due to its highly exothermic, chain-propagating nature.

Why the others are wrong:

• A: Iodine oxidizes reducing agents like thiosulfate, confirming its oxidizing ability.
• B: Larger iodine molecules have higher boiling points, reducing volatility.
• D: Concentrated H₂SO₄ with NaBr yields Br₂, SO₂, H₂O, and HBr, but not H₂S.

Final answer: C