I. Make solutions of each and look for a precipitate when added to 0.10 M Ba(NO3)2. II. Add crystals of each to 0.10 M HCl and watch for bubbles. III. Make solutions of each and test with a pH indicator.
The answer is II and III only. I understand how III works, but I don't see how sulfite and sulfate can be differentiated by adding HCl; don't both get reduced to SO2 bubbles?