Answer :
Answer: [tex]BaF_{2}[/tex]
Explanation: Because barium is in Group 2, it forms ions with a charge of +2. Fluorine, in Group 17, form ions with a charge of -1. Cross the charges to get the subscripts (Since Ba has a charge of +2, F has a subscript of 2. Because F has a charge of -1, Ba needs a subscript of 1). Therefore, a formula unit of the compound is [tex]BaF_{2}[/tex].