In the cyanide extraction process of silver from argentite ore, the oxidising and reducing agents used are

The reactions involved in extraction of silver by cyanide process areAg2S+CN−+O2⟶Ag(CN)2+SO2...........(i)Ag(CN)2+Zn⟶Zn(CN)42−+Ag........(ii)In reaction (i), sulphide is oxidised to SO2 by oxygen.In the reaction (ii), silver ion (Ag+) is reduced to Ag by Zn.Therefore,O2 is oxidising agent and Zn is reducing agent.