Final answer:
In the reaction FeO(s) + CO(g) → Fe(s) + CO₂(g), iron in FeO is reduced, while carbon in CO is oxidized.
Step-by-step explanation:
In the given reaction FeO(s) + CO(g) → Fe(s) + CO₂(g), the element iron in FeO is being reduced. Reduction is a process where an element gains electrons or decreases its oxidation number. In this case, the oxidation number of iron goes from +2 in FeO to 0 in Fe, indicating reduction.
On the other hand, the element carbon in CO is being oxidized. Oxidation is a process where an element loses electrons or increases its oxidation number. In this case, the oxidation number of carbon goes from +2 in CO to +4 in CO₂, indicating oxidation.