Answer:

hello tanu,

here in this formula magnesium hydrogencarbonate;

first we write Symbol of the element and then we will write the valency:

so first,Symbol:Mg and the valency of Mg=2,the symbol of hydrogencarbonate:HCO3-  and the valency is 1,so we cross mutiply mg and HCO3- and hence after cross multiplying the answer will be Mg(HCO3-)2.

simple and easy,you just cross mutiply it and answer will be coming this only.

Explanation: