Question 12.Give reasons :(a) Platinum, gold and silver are used to make jewellery.(b) Sodium, potassium and lithium are stored under oil.(c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.

(a) Platinum, gold and silver are used to make jewellery because these are malleable and ductile. These are highly resistant to corrosion. (b) Sodium, potassium and lithium are very reactive and catch fire when exposed to air. This is due to their low ignition temperature and high reactivity. (c) Aluminium forms a non-reactive layer of aluminium oxide on its surface. This layer prevents aluminium to react with other substances. That’s why aluminium is used to make cooking utensils. (d) It is easier to reduce a metal oxide into free metal. Since it is easier to obtain metals from their oxides than from their carbonates or sulphides directly, therefore, the carbonate and sulphide ores are first converted to oxides for extracting the metals.