An aqueous solution of copper(II) sulfate is electrolysed with copper electrodes. What is the ionic half-equation for the process at the cathode?
- A$\text{Cu} \rightarrow \text{Cu}^{2+} + 2e^-$
- B$\text{Cu}^{2+} + 2e^- \rightarrow \text{Cu}$
- C$2\text{H}^+ + 2e^- \rightarrow \text{H}_2$
- D$2\text{O}^{2-} \rightarrow \text{O}_2 + 4e^-$