Chlorine Disproportionation in Aqueous Solution

Steps:

• Assign oxidation states: In Cl₂, Cl is 0; in H₂O, H is +1 and O is -2.
• In products, Cl in HOCl is +1 (H +1, O -2, so Cl +1); Cl in Cl⁻ is -1; H in H⁺ is +1.
• One Cl atom oxidizes from 0 to +1 in HOCl, losing electrons.
• Another Cl atom reduces from 0 to -1 in Cl⁻, gaining electrons.

Why A is correct:

• This is a disproportionation reaction, where chlorine is simultaneously oxidized and reduced, per the definition of redox processes involving the same element.

Why the others are wrong:

• B: Chlorine is also reduced to Cl⁻, not just oxidized.
• C: Hydrogen's oxidation state remains +1 in both H₂O and H⁺, so it is neither oxidized nor reduced.
• D: Identical to C; hydrogen shows no redox change.

Final answer: A