What tests could be used to confirm the presence of Na3PO4? Select all that apply. Flame test Adding ammonium oxalate to look for a white precipitate adding sodium hydroxide and check for ammonium ions with red litmus paper add nitric acid and potassium thiocyanate to look for a red precipitate add silver nitrate and nitric acid and look for a white precipitate add barium chloride and nitric acid to look for a white precipitate add nitric acid and ammonium molybdate to look for a white precipitate add hydrochloric acid to look for the evolution of gas.