Atoms of \(\ce{Mg}\) combine with atoms of \(\ce{F}\) to form a compound. Atoms of which of the following elements combine with atoms of \(\ce{F}\) in the same ratio?

Magnesium will form the cation \(\ce{Mg^{2+}}\). Fluorine forms \(\ce{F-}\). In order to form a neutral compound, two atoms of fluorine will bond with one atom of magnesium to form \(\ce{MgCl2}\).

Barium \(\ce{Ba}\) is in the same periodic group as magnesium and will also form the cation \(\ce{Ba^{2+}}\).