Question

To form a stable ion will magnesium gain or lose electrons how many electrons

Answer 1

The electronic structure of Magnesium is 2,8,2
so in order to form a stable ions, it will lose 2 electrons.
Now, the proton number of Mg is 12, electron number is 10.
It will show positive charge.
Conclusion: Mg will lose 2 electrons to form Mg2+.