How do you predict single-replacement reactions that include compunds?

NO3 has a charge of negative 1 per NO3 ion, the best way to learn these is to (i hate to say it) memorize the common ions and their charges, monatomic ions (Cl-, F-....) can be derived from the periodic table most of the time based on their position, metals are a bit more challenging and either need a oxidation state provided or they just have ONE that they like to use all the time (personifying elements). polyatomic Ions having more the one atom, you really need to memorize. But once you can find out, or know the charge, you should be able to do these sort of problems easily.