For the oxidation of iodide ion by hydrogen peroxide in acidic solution, the mechanism below has been proposed:
Step 1 (slow): MnO₂ + 2 I⁻ + 4 H⁺ → Mn²⁺ + I₂ + 2 H₂O
Step 2 (fast): Mn²⁺ + H₂O₂ → MnO₂ + 2 H⁺
(i) Identify the catalyst in the mechanism.
(ii) Identify the intermediate in the mechanism.
Briefly justify each choice.