Disproportionation reaction of chlorine

Steps:

• Reaction with cold dilute NaOH: Cl₂ + 2NaOH → NaCl + NaClO + H₂O.
• Oxidation states: Cl in Cl₂ is 0; in Cl⁻ is -1; in ClO⁻ is +1.
• Some Cl atoms reduced (0 to -1); others oxidized (0 to +1).
• Chlorine undergoes both oxidation and reduction simultaneously.

Why A is correct:

• Disproportionation defines a reaction where the same element is both oxidized and reduced, as seen in Cl oxidation states changing from 0 to -1 and +1.

Why the others are wrong:

• B: Chlorine experiences both redox processes, not neither.
• C: Chlorine is also reduced to Cl⁻.
• D: Chlorine is also oxidized to ClO⁻.

Final answer: A