Electrolysis of CuSO4(aq) with Cu electrodes transfers Cu from anode to cathode

Steps:

• Cu²⁺ ions from electrolyte reduce at cathode: Cu²⁺ + 2e⁻ → Cu, depositing Cu and increasing cathode mass.
• Cu atoms oxidize at anode: Cu → Cu²⁺ + 2e⁻, dissolving Cu and decreasing anode mass.
• Released Cu²⁺ ions replace deposited ones, maintaining blue color of electrolyte.
• No gas evolution or other changes occur under these conditions.

Why C is correct:

• Matches Cu transfer: anode loses mass via oxidation, cathode gains mass via reduction, Cu²⁺ concentration stays constant per Faraday's laws of electrolysis.

Why the others are wrong:

• A: Anode decreases (not increases) and cathode increases (not decreases) in mass.
• B: Anode decreases (not stays same) and cathode increases (not decreases); color stays blue (not colourless).
• D: Anode decreases (not stays same); color stays blue (not colourless).

Final answer: C