Final answer:
In the cyanide extraction process of silver from argentite ore, oxygen is used as the oxidizing agent and zinc dust is the reducing agent. The correct option for the oxidizing and reducing agents used is (B) O₂ and Zn dust, respectively.
Step-by-step explanation:
In the cyanide extraction process of silver from argentite ore, oxygen (O2) is used as the oxidizing agent to react with silver and produce dicyanoargenate(I) ions. This reaction requires the presence of oxygen to convert the silver into the soluble complex:
4Ag(s) + 8CN−(aq) + O2(g) + 2H2O(l) → 4[Ag(CN)2]−(aq) + 4OH−(aq)
The precipitating agent, or the reducing agent, used is zinc dust. Zinc reduces the silver cyanide complex to free silver:
2[Ag(CN)2] −(aq) + Zn(s) → 2Ag(s) + [Zn(CN)4] 2−(aq)
Based on this information, option (B) O2 and Zn dust as the oxidizing and reducing agents, respectively, is correct for the process of silver extraction from argentite ore using cyanide.