Disproportionation reactions of chlorine with NaOH at different temperatures

Steps:

• Cold NaOH reaction: Cl₂ + 2NaOH → NaCl + NaClO + H₂O; X is NaClO (hypochlorite).
• In NaClO, Cl oxidation state: let x be Cl state, x - 2 = -1 → x = +1.
• Hot NaOH reaction: 3Cl₂ + 6NaOH → 5NaCl + NaClO₃ + 3H₂O; Y is NaClO₃ (chlorate).
• In NaClO₃, Cl oxidation state: x + 3(-2) = -1 → x = +5.

Why D is correct:

• Oxidation state rules confirm Cl as +1 in ClO⁻ and +5 in ClO₃⁻, matching the products X and Y.

Why the others are wrong:

• A: -5 impossible for chlorine (max +7); Y is +5.
• B: -5 impossible; Y is +5, not -5.
• C: X is +1 (hypochlorite), not -1 (chloride).

Final answer: D