21. Solving a chemistry problem

9. The cathode compartment of the cell for internal electrolysis contains 100 ml of cobalt solution with a concentration of 0.100 g-ion/l and a cobalt cathode. The anode is a magnesium electrode immersed in 20.0 ml of a solution with a Mg2 concentration of 1.00∙10-3 g-ion/l. Cell resistance 7.5 ohm. Define:
a) The initial potential of this cell before current flows,
b) Current when the electrodes are short-circuited.