E. Short Answer Type Questions
1. What is the difference between ore and
mineral?
2. Why is phosphorus stored in water
and sodium kept immersed in kerosene?
3. Write any two uses each of metals and
nonmetals.
4. Why is jewellery generally made from
silver, gold and platinum?
5. Zinc metal can displace copper from
copper sulphate solution. Explain with
reason.
6. Vessels made of metals lose their shine
with time. Why?
Answers
1. Minerals are naturally occurring inorganic solids with a crystalline structure and a definite range of chemical formula. Ores are concentrations of minerals in rock that are high enough to be economically extracted for use.
2.It is kept immersed in kerosene oil to protect it from the action of oxygen, moisture and carbon dioxide of air and to prevent accidental fires. (b) White phosphorus is kept immersed in water because it reacts spontaneously with oxygen of air to form phosphorus pentoxide but does not react with water
3.Copper is used for making electrical wires, cooking utensils, etc. Zinc is mainly used as a protective coating for iron. Aluminium is used for making electrical cables, packaging, cooking utensils, etc. Non-metals Hydrogen is used for the synthesis of ammonia and methyl alcohol, in welding torches, etc.
4.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.
5.(i) Zinc metal can displace copper from copper sulphate solution because zinc is more reactive than copper. (ii) Copper cannot displace zinc from zinc sulphate solution because copper is less reactive than zinc.
6. This is due to the process of corrosion or tarnishing. In this process, the metals reacts with elements in the environment like oxygen, carbon or sulphides to form hrdroxides, oxides, sulphides or carbonates. These compounds formed are dull and responsible for the loss of the shinny nature of the vessels.
1.Minerals are naturally occurring chemical substances. They are present in earth's crust and obtained by mining. Ores are the minerals from which a metal can be economically and conveniently extracted.
Thus, Bauxite and clay are minerals of Al. However, bauxite is an ore of Al as Al can be economically and conveniently extracted from bauxite.
2.phosphorus is kept immersed in water because it reacts spontaneously with oxygen of air to form phosphorus pentoxide but does not react with water.
Sodium is very reactive metal so it reacts vigorously with the oxygen of air and catches fire. It is kept immersed in kerosene oil to protect it from the action of oxygen, moisture and carbon dioxide of air and to prevent accidental fires.
3.Metals Iron is used for making automobiles, machinery, pipes, containers, nails, etc. Gold and silver are used for making jewellery. Copper is used for making electrical wires, cooking utensils, etc. Zinc is mainly used as a protective coating for iron. Aluminium is used for making electrical cables, packaging, cooking utensils, etc.
Non-metals Hydrogen is used for the synthesis of ammonia and methyl alcohol, in welding torches, etc. Sulphur is used in the manufacture of compounds like sulphuric acid and sulphates and in the production of matches, dyes, and gunpowder. Graphite is used in pencils, in zinc-carbon batteries, and in brake linings. Phosphorus is used in the fireworks industry and for making special glasses used in sodium lamps.
4.Platinum, gold and silver are used to make jewellery because these are low reactive metals. So they rarely corrode and hence do not lose their shine and lustre.
5.Zinc can displace copper from copper sulphate solution zinc is less stable than copper and hence more reactive than copper.
6.Vessels made up of metals lose their shine after few days because of the effects caused by air and water in the atmosphere which results in the corrosion of their surface .
These are the answers for your questions hope it helps u