Question

electronic configuration of MG ++ (at number equals to 12)
​

Answer 1

Mg ++ or Mg²+ or Mg+²

All are same!

Now Mg²+ is a positive charged ion that is Cation.

As this a Mg atom which has 12 electrons and Mg looses it's two elctrons and became a cation(Mg²+) and the electron configuration of a simple or nutral Mg atom is

Mg= 2, 8, 2

or 1S² 2S² 2P6 3S²

And the electron configuration of Mg²+ ion is

Mg²+ = 2 , 8

or 1S² 2 S² 2P6