Haber Process Catalyst Identification

Steps:

• Recall the Haber process synthesizes ammonia from nitrogen and hydrogen.
• Identify the catalyst as finely divided iron, often with promoters.
• Note the active form is metallic iron, reduced from iron(III) oxide.
• Determine iron's oxidation state in metallic form as 0.

Why B is correct:

• The Haber process uses iron metal (Fe) as the catalyst, where iron has an oxidation number of 0 in its elemental state.

Why the others are wrong:

• A: Iron is reduced to oxidation state 0; +3 applies to the precursor oxide, not the active catalyst.
• C: Vanadium is the catalyst in the Contact process for sulfuric acid, not Haber.
• D: Same as C; vanadium is irrelevant to the Haber process.

Final answer: B