Question

Assertion (A): Electrolysis of aqueous solution of NaCl gives chlorine gas at anode instead of oxygen gas. Reason (R): Formation of oxygen gas at anode requires overpotential.

Four half reactions I to IV are shown below : I. 2Cl⁻ → Cl₂ + 2e⁻, II. 4OH⁻ → O₂ + 2H₂O + 2e⁻, III. Na⁺ + e⁻ → Na, IV. 2H⁺ + 2e⁻ → H₂. Which two of these reactions are most likely to occur when concentrated brine is electrolysed ?