In a blast furnace, which statement describes how iron is separated?

• A. Coke burns in O2 and forms CO
• B. CO and iron oxide reduces to iron and CO2
• C. Limestone dissolves iron
• D. Hydrogen reduces iron oxide

Answer: (B)

In a blast furnace, iron is produced by reducing iron oxide with carbon monoxide that comes from the coke. The carbon monoxide removes oxygen from the iron oxide to form iron and carbon dioxide, as shown by the simplified reaction Fe2O3 + 3 CO → 2 Fe + 3 CO2. This reduction step is the key way iron separates from its ore in the furnace. Limestone is added mainly as a flux to form slag with impurities, not to dissolve iron. Hydrogen isn’t used as the reducing agent in this setup. So the process described—carbon monoxide reducing iron oxide to iron with carbon dioxide produced—best explains how iron is separated.