Question

How many unpaired electrons are in a Mg atom?

Answer 1

In the ground state of magnesium, none of the valence electrons are unpaired.

Explanation:

The ground state of Mg is `1s^2 2s^2 2p^6 3s^2` so you see that the valence electrons are paired in the `3s` subshell. No valence electrons are unpaired here.