1)Gold ans silver are used to make jewellery.
2)Carbonate and sulphide ores are usually converted into oxides prior to reduction during the process of extraction.
1) Gold and Silver are used for making jewellery because they hardly react with water that 's why they didn 't get rust and they look superior they are not destroyed by chemical reaction...
Gold and silver are used to make jewellery because they are precious and expensive metals. Also, gold and silver last very long and look luxurious.
2) Conversion of concentrated ore into metal oxide
It is easier to obtain metals from their oxides rather than from carbonates or sulphides. So the ore is first converted into an oxide. A carbonate ore is first converted into oxide ore by calcination. A sulphide ore is converted into oxide ore by roasting.
1. Calcination process
It is the process of heating the concentrated ore at a temperature not sufficient to melt the ore. The water content and the volatile impurities also get expelled. Zinc carbonate in its ore calamine (ZnCO3) is calcinated to obtain zinc oxide (ZnO).
2. Roasting process
It is the process of heating the concentrated ore in the presence of excess air. Volatile impurities also get expelled.
Zinc sulphide in its ore zinc blende ( ZnS) is roasted to obtain zinc oxide (ZnO).
Mercuric oxide is obtained by roasting cinnabar (HgS) in air.