To determine which substances might be involved in an oxidation-reduction reaction that would result in the formation of ions, set-up the balanced equation for each pair:
Aluminum and Oxygen
Al3+ + O2 ===> Al2O3
Sulfur and Oxygen
2S + 5/2O2 ===> SO2 + SO3-2
Carbon and Oxygen
C + O2 ===> CO2
Thus, only sulfur and oxygen produces ions in a Re-Dox reaction.
