The answer is (1) 10. The protons of Mg atom is 12. So the Mg atom has 12 electrons. The Mg2+ ion has lost two electrons so it has two positive charge. Then the answer is 10 electrons.
the cathode is where reduction occurs!
C becuase that is the one that you would have to do becuase that is the only option
Lanthanide belongs to period 6, and actinides belongs to period 7