The diagram shows an electrolysis experiment. Which reaction occurs at the anode and which reaction occurs at the cathode for this experiment?

Answer:

2) E

You must first know what anodes and cathodes are.

The anode which is made out of copper, will form positive copper ions. So the reaction at the anode would be:
Cu → Cu²⁺ + 2e⁻

These positive copper ions will then travel to the cathode and form copper atoms. The reaction would be:
Cu²⁺ + 2e⁻ → Cu