An aqueous solution of nickle [II] sulphate was electrolyzed using nickle electrodes. Observe the diagram and answer the questions that follow:

(i) What do you observe at the cathode and anode respectively.

(ii) Name the cation that remains as a spectator ion in the solution.

(iii) Which equation for the reaction at the anode is correct.

1. Ni ⟶ Ni²⁺ + 2e^-
2. Ni + 2e^- ⟶ Ni²⁺
3. Ni²⁺ ⟶ Ni + 2e^-
4. Ni²⁺ + 2e^- ⟶ Ni

(i) The observations at cathode and anode are:
At cathode: Ni²⁺ ions move towards cathode and are discharged as neutral Ni atoms by gain of electrons. Thus, Ni is deposited at cathode.
At anode: Diminishes in mass. Ni²⁺ ions are formed.

(ii) H⁺ ions.

(iii) Ni ⟶ Ni²⁺ + 2e^-