6. A student did experiment 1 and saw the following results. Upon adding HCl to the unknown mixture, there was a white precipitate. Then pon addition of the ammonia solution, there was no precipitate. When (NH4)2C204 is added, a white precipitate forms. Nitric acid is added to the solution, and this is dried. The residue is reconstituted in a hydrochloric acid solution, and then sodium hydroxide is added. Upon heating a precipitate forms. The solution turns yellow upon addition of Na3 Co(NO2) What cations are present in the unknown