Catalysts in Haber and Contact Processes

Steps:

• Identify Haber process catalyst: finely divided iron (Fe) with promoters like K2O and Al2O3; iron is in elemental form, oxidation state 0.
• Note question's second part asks for oxidation number in Contact process catalyst.
• Recall Contact process catalyst: vanadium(V) oxide (V2O5) for SO2 to SO3 conversion.
• Determine oxidation state in V2O5: oxygen is -2, so 2V + 5(-2) = 0 → V = +5.

Why D is correct:

• Vanadium in V2O5 has +5 oxidation state, as calculated from the formula where V2O5 is neutral.

Why the others are wrong:

• A: Iron in Haber catalyst is 0, not +3; +3 occurs in compounds like Fe2O3, not the active catalyst.
• B: No option provided.
• C: Duplicate of D; no distinction.

Final answer: D