Electrolysis products identify the electrolyte as dilute sulfuric acid

Steps:

• Observe gas evolution at electrodes: colorless gas at cathode (2 volumes) and anode (1 volume).
• Identify cathode gas as hydrogen (ignites with pop) and anode gas as oxygen (relights splint).
• Confirm 2:1 volume ratio matches water decomposition: 2H₂O → 2H₂ + O₂.
• Rule out other options by mismatched products or electrode reactions.

Why C is correct:

• Dilute H₂SO₄ electrolyzes water (H₂SO₄ acts as catalyst): cathode 2H⁺ + 2e⁻ → H₂; anode 2H₂O → O₂ + 4H⁺ + 4e⁻, yielding H₂ and O₂ in 2:1 ratio.

Why the others are wrong:

• A: Cathode deposits Cu metal, not H₂ gas.
• B: Anode produces Cl₂ gas (greenish-yellow), not O₂.
• D: Ethanol decomposes to H₂ and ethanal/CO₂, no clean 2:1 H₂:O₂ ratio.

Final answer: C