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.

Explanation

Platinum , gold and silver are used to make jewellary because of their bright shiny surface and high resistance to corrosion. Also, they have high malleability and ductility.
(ii)Sodium, potassium and lithium are stored under oil to prevent their reaction with oxygen, moisture and carbon dioxide of air so as to protect them because they are very reactive metals.
(iii)Aluminium metal forms a thin layer of aluminium oxide all over its surface, under the action of moist air. This layer prevents the metal underneath from further corrosion. It is cheap, easily available,malleable,ductile and a good conductor of heat. Therefore, it is used to make utensils for cooking.
(iv)It is easier to obtain a metal from its oxides as compared to its sulphides and carbonates. So prior to reduction, metal carbonate and sulphides must be converted into metal oxides. A carbonate ore is converted into oxide by calcination, whereas a sulphide ore is converted into oxide by roasting.