Final answer:
The oxidizing agent in the reaction Fe₂O₃ + 3CO → 2Fe + 3CO₂ is the iron (III) ion, Fe³+, found in Fe₂O₃.
Step-by-step explanation:
In the reaction Fe₂O₃ + 3CO → 2Fe + 3CO₂, the element that is the oxidizing agent is iron (III) ion within Fe₂O₃. The carbon monoxide (CO) acts as the reducing agent since it contains the element that is oxidized (carbon). The oxidation state of carbon increases from +2 in CO to +4 in CO₂, indicating that it has been oxidized. Conversely, the iron (III) ion's oxidation number decreases from +3 in Fe₂O₃ to 0 in Fe, signifying reduction. Hence, since Fe³+ is being reduced, it serves as the oxidizing agent in this reaction.