Final answer:
During the electrolysis of copper II tetraoxosulphate IV, copper is oxidized at the anode, and copper ions migrate to the cathode. At the cathode, the copper ions are reduced, forming solid copper.
Step-by-step explanation:
During the electrolysis of copper II tetraoxosulphate IV, copper is oxidized at the anode, and copper ions migrate to the cathode. At the cathode, the copper ions are reduced, forming solid copper. Therefore, the correct answer is option B - Copper ions are reduced at the cathode, forming solid copper.