Give reasons

(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.

Answer

(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.

It is not easy to reduce naturally occurring carbonate and sulphides directly into metals. 

• The process involves extra steps and is not commercially viable
• Hence, they're first converted into oxides . 

After an ore is converted into oxide, it is easier to reduce them into pure metals.