Electrolysis electrode reactions and solution changes Steps:

• Cathode (negative electrode): Reduction occurs; H⁺ ions from acid gain electrons to form H₂ gas.
• Anode (positive electrode): Oxidation occurs; H₂O molecules lose electrons to form O₂ gas and H⁺ ions.
• Overall reaction: 2H₂O → 2H₂ + O₂; water is converted to gases that escape, reducing solution volume.
• Acid concentration increases as H₂SO₄ ions remain while volume decreases.

Why D is correct:

• Anode produces O₂ via water oxidation, cathode produces H₂ via H⁺ reduction, and water loss concentrates the acid per the overall decomposition reaction.

Why the others are wrong:

• A: Correct electrode products but wrong concentration (it increases, not decreases).
• B: Swaps electrode products (H₂ at cathode, O₂ at anode) and wrong concentration.
• C: Swaps electrode products but correct concentration.

Final answer: D