In the equation, 4M+8CN– + 2H2O + O2-> 4 [M(CN)2]– + 4OH–, the metal M is

Cyanide process is carried out to obtain less reactive metals like gold and silver. The impure metal is treated with NaCN solution in presence of air. The metal then forms a soluble complex. The reaction is- - - - 2 2 2 4Au+8CN +2H O+O 4[M(CN) ] +4OH -> Extraction of Iron and Copper 52. Which ore contains both iron and copper? (a) Cuprite (b) Chalcocite (c) Chalcopyrite (d) Malachite The molecular formula of cuprite is 2 Cu O . The molecular formula of chalcocite is 2 Cu S . The molecular formula of chalcopyrite is 2 CuFeS , and the molecular formula of malachite is 2 3 Cu(OH) .CuCO . So,