Electrode reactions in aluminum electrolysis Steps:

• Cathode is site of reduction: Al³⁺ ions from the melt gain 3 electrons to deposit Al metal.
• Anode is site of oxidation: O²⁻ ions from the melt lose 4 electrons to form O₂ gas (balanced as 2O²⁻ → O₂ + 4e⁻).
• Eliminate options with reversed or mismatched half-reactions.
• Select option assigning Al reduction to cathode and O oxidation to anode.

Why D is correct:

• Matches electrolysis rules: reduction (Al³⁺ + 3e⁻ → Al) at cathode deposits metal; oxidation (O²⁻ to O₂) at anode releases oxygen, per electrode definitions.

Why the others are wrong:

• A: Reverses electrodes—reduction cannot occur at anode.
• B: Shows anode reaction as reduction (electrons gained), contradicting oxidation requirement.
• C: Uses unbalanced equation for anode (single O²⁻ cannot yield O₂ without 2O²⁻).

Final answer: D