Question

An unknown compound has the following chemical formula: where stands for a whole number. Measurements also show that a certain sample of the unknown compound contains of magnesium and of chlorine. Write the complete chemical formula for the unknown compound.

Answer 1

Answer:  This is only a guess:  The "following chemical formula:      " doesn't appear on my screen.  But since you mentioned Mg and Cl, I would guess MgCl2

Explanation:  Mr loses 2 electrons while each Cl gains one each:  Two chlorines for every 1 magnesium.