Question

The molecular formula of magnesium chloride is:

• A. ${\text{MgCl}}_4$
• B. ${\text{MgCl}}_3$
• C. ${\text{MgCl}}_2$
• D. $\text{MgCl}$

Answer 1

The correct option is C ${\text{MgCl}}_2$

Molecular formula is the representation of the atoms present in the molecule of an element or compound. $$\begin{array}{cccc}\text{Element}& \text{Atomic no.}& \text{Electronic configuration}& \text{Valency}\\ \text{Magnesium}& \text{12}& \text{2, 8, 2}& \text{2}\\ \text{Chlorine}& \text{17}& \text{2, 7}& \text{1}\end{array}$$ To get molecular formula of magnesium chloride we need to cross multiply the valencies of these elements as shown below.

Element Mg Cl
$\searrow \swarrow$
Valency 2 1

Hence, the molecular formula of magnesium chloride is ${\text{MgCl}}_2$.