Answer: coke (carbon).
- A carbon monoxide (CO)
- B coke (carbon)
- C limestone
- D hydrogen gas
Correct answer: B. coke (carbon)
Explanation: In the very hot lower region (about 1123-1873 K) the FeO is reduced directly by coke (carbon): FeO + C gives Fe + CO; in cooler upper zones CO is the main reductant.
An Ellingham diagram plots ΔG° of oxide formation against temperature for different metals; whichever line is LOWER (more negative ΔG°) at a given temperature reduces the oxide of any metal whose line sits above it - the basis of carbon reduction (Fe, Zn) vs electrolytic reduction (Al, Mg, Na) decisions.
Concept context
The science of extracting metals from ores and refining them for use. Covers concentration methods, reduction techniques, refining processes, and the thermodynamic principles that govern metal extraction.