Writing formula for compounds!? (check my answers for me?)

Write the correct formula for each of the following compounds:

1) Nitrogen trioxide: NO3
2) Aluminum sulfide: AlS
3) Potassium chloride: KCl
4) Phosphorus tetraoxide: PO4
5) Sodium iodide: NaI
6) Uranium (VI) flouride: UF
7) Chlorine dioxide: ClO2
8) Lithium phosphide: Li3P
9) Calcium sulfide: CS
10) phophorus pentoxide: PO5
11) lead (II) oxide: PbO
12) Iron (III) sulfide: FeS

2. Al2S3

6. UF6

9. CaS

12. Fe2S3

Watch your oxidation numbers when writing formulas!