Answer:
B. Two chlorine atoms
Explanation:
This electronic configuration shows that the given atom is magnesium.
Electronic configuration of magnesium:
Mg¹² = 1s² 2s² 2p⁶ 3s²
There are two valance electrons of magnesium that's why it would react with two atoms of chlorine. Chlorine is present in seventeen group. It has seven valance electrons. It required just one electron to get complete octet. While magnesium needed to lose two electrons to get complete octet. That's why two chlorine atoms bonded with one magnesium atom. Thus both would get complete octet.
Mg + Cl₂ → MgCl₂
