Writing Formulas of Binary Ionic compounds

Writing Formulas of Binary Ionic compounds (metals have fixed oxidation numbers

Given the names, write the formulas of the following compounds.

1.magnesium oxide

2. lithium bromide

3.potassium chloride

4.calcium sulfide

5.sodium fluoride

6.How many sodium atoms are there in one formula unit of sodium oxide?

7.How many barium atoms are there in one formula unit of barium phosphide?

8.How many atoms of nitrogen are there in one formula unit of calcium nitride?

9.How many atoms of bromine are there in one formula unit of aluminum bromide?

10.How many atoms of sulfur in one formula unit of lithium sulfide