Sulfuric acid oxidizes iodide but not chloride

Steps:

• Concentrated H2SO4 reacts with NaCl to form HCl, indicating no oxidation of Cl⁻.
• With NaI, I₂ forms, showing oxidation of I⁻ to I₂ by H2SO4.
• H2SO4 acts as an oxidizing agent in these reactions.
• Standard reduction potential for I₂/2I⁻ (+0.54 V) is lower than Cl₂/2Cl⁻ (+1.36 V), so I⁻ is easier to oxidize.

Why B is correct:

• Iodide ions are more easily oxidized than chloride ions, as their lower reduction potential means H2SO4 can oxidize I⁻ to I₂ but not Cl⁻ to Cl₂.

Why the others are wrong:

• A: Chloride ions are harder to oxidize than iodide, not easier.
• C: Sulfuric acid acts as an oxidizing agent here, not reducing.
• D: Sulfuric acid is not a reducing agent, and iodide ions are harder to reduce than chloride.

Final answer: B