Answer: Gold.
- A Gold
- B Iron
- C Zinc
- D Aluminium
Correct answer: A. Gold
Explanation: Unreactive (noble) metals such as gold occur in the native, uncombined state, whereas reactive metals like iron, zinc and aluminium are always found as compounds.
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.