An unknown solution may contain one or more of the following anions ( SO42-, PO43-, Cl-, and NO3-): A student received a sample of the above unknown and then performed the required procedure to determine which anion in the unknown as following: 1st half of the sample: a) The addition of aqueous barium nitrate to the basified solution yields a white precipitate which then separated from the solution (the solution kept for step b) by the centrifuge. The precipitate was dissolved by the addition of HNO3. The solution was separated from the remaining solid and treated with ammonium molybdate which results in the formation of a yellow precipitate. b) The solution was acidified with 6M HCl before the addition of aqueous silver nitrate which forms a precipitate. This precipitate is then basified with 6M aqueous ammonia and the precipitate completely dissolves. 2nd half of the sample: An unknown solution was acidified with 6M H2SO4. no observation was shown after the addition of excess FeSO4 solution and Conc. H2SO4. Which anions were present in the student’s unknown? Select one or more: SO42- PO43- Cl- NO3-