Question

Copper and silver are below hydrogen in electrochemical series and yet they are found in the combined state as sulphides in nature. Comment.

Answer 1

Copper and silver are below hydrogen in the electrochemical series, meaning they are less reactive than hydrogen. However, their cations (Cu⁺ and Ag⁺) have high polarising power due to their electronic configuration (d¹⁰s²). This makes their sulphides very stable. Thus, copper and silver occur naturally as stable sulphide ores rather than in the free metallic state.