The atomic number of magnesium is 12, it will achieve its stable electronic configuration by donating _______ number of electrons.

The correct option is D

2

The explanation for the correct option (D):

Octet rule: The octet rule states that every atom to attain stability must be filled with " $8$ " electrons in its outermost electron shell.

• As the number of electrons in the outer shell of the most stable or inert atoms is $8$.

$\mathrm{Magnesium}\left(\mathrm{Mg}\right)$: The atomic number of $\mathrm{Magnesium}\left(\mathrm{Mg}\right)$ is$12$, So there are $12$ electrons and its electronic configuration is $2\left(\mathrm{K}\right),8\left(\mathrm{L}\right),2\left(\mathrm{M}\right).$

• Here, the M shell will be its valence shell with 2 electrons.
• It will achieve its stable electronic configuration like Neon(Ne) 10: $2\left(\mathrm{K}\right),8\left(\mathrm{L}\right)$ by donating these two valence electrons.

Thus, option (D) i.e., 2 is the correct option.