The correct option is C MgCl2
Molecular formula is the representation of the atoms present in the molecule of an element or compound. ElementAtomic no.Electronic configurationValencyMagnesium 122, 8, 22Chlorine172, 71 To get molecular formula of magnesium chloride we need to cross multiply the valencies of these elements as shown below.
Element Mg Cl
Valency 2 1
Hence, the molecular formula of magnesium chloride is MgCl2.