QuestionMetallurgy / occurrence of metals
Which one of the following pairs of elements is found in the free state?
- (a) Gold and Platinum
- (b) Copper and Silver
- (c) Gold and Silver
- (d) Copper and Platinum
Answer: (a) Gold and Platinum
Metals at the bottom of the activity series are so unreactive that they occur native (free). Gold and platinum are almost always found free. Copper and silver occur mainly as sulfide ores (Cu₂S, CuFeS₂, Ag₂S) and only occasionally native, so any pair containing Cu or Ag is weaker. Remember: Au, Pt (and other platinum metals) are the classic 'noble' metals found in the free state → (a).