A sulphide ore is first converted into its oxide before reduction. This is done because : — Metallurgy and Isolation of Elements Chemistry Question

💡 Solution & Explanation

Step 1: Pyrometallurgy involves the thermal treatment of minerals to retrieve the constituent metals. However, highly stable compounds or highly noble metals like Silver (Ag) are usually extracted via hydrometallurgical processes (like cyanide leaching) rather than pyrometallurgical reduction of their sulfides (Ag2S). Step 2: While ZnS is roasted and reduced, Ag2S extraction is primarily commercialized via hydrometallurgy because silver is a precious metal with low reactivity, and smelting Ag2S directly has low yield and high losses. Step 3: Therefore, the pair Ag2S and ZnS contains ores that are not both typically extracted/converted by pyrometallurgy alone (especially Ag2S), making option (a) the correct choice.