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
Answers
Answer:
a)
Platinum Gold and silver are used to make jewellery because of the following reasons. They are highly lustrous metals which are resistant to corrosion. They are highly malleable and ductile so can be transformed into any shape or design.
b) Sodium, potassium, and lithium are stored under oil because metals like sodium and potassium react so, vigorously that they catch fire if kept in the open. Hence, to protect them they are kept immersed in kerosene oil.
c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking. ... This is because aluminium reacts with oxygen present in air to form a thin layer of aluminium oxide. This oxide layer is very stable and prevents further reaction of aluminium with oxygen.
d)Carbonate and sulphide ores are usually converted into oxides during the process of extraction because extraction of metal is easier from their oxides rather than from their carbonates or sulphides.
Answer:
a.)Platinum, gold and silver are used to make jewellery because the metals used in jewellery are always be chosen on the basis of its reactivity. They are highly lustrous metals which are resistant to corrosion. They are highly malleable and ductile so can be transformed into any shape or design.
b.)Sodium, potassium, and lithium all are alkali metals. All belong to the group-first. Alkali metal forms oxides in presence of oxygen. Therefore, due to the high reactivity of alkali metals towards air and moisture, they are stored in kerosene oil.
c.)Aluminium is a highly reactive metal, yet it is used to make utensils for cooking. This is because aluminium reacts with oxygen present in air to form a thin layer of aluminium oxide. This oxide layer is very stable and prevents further reaction of aluminium with oxygen.
d.)Carbonate and sulphide ores are usually converted into oxides during the process of extraction because extraction of metal is easier from their oxides rather than from their carbonates or sulphides.