Vivekanand Vellanki

Criss cross method:

1) Find the oxidation number for the elements. I believe Mg is +2 and Cl is -1

2) Find the HCF of the oxidation numbers and divide both by the HCF. In this case, the HCF is 1 - nothing to be done

3) Criss the oxidation numbers and apply them to other elements.

Oxidation number of Mg is applied as a subscript of Cl; and the oxidation number of Cl is applied as a subscript for Mg.

You get MgCl_2