1) Balanced chemical reaction: Cl₂ + 2NaI → 2NaCl + I₂. Chlorine and iodine are diatomic molecules. 2) Balanced chemical reaction: 2NH₃ → N₂ + 3H₂. Nitrogen and hydrogen are diatomic molecules. 3) Balanced chemical reaction: 4Na + O₂ → 2Na₂O. Sodium in compounds has oxidation number +1 and oxygen -2.