NCERT Solutions for Class 8 Social Science Chapter 3 : Mineral and Power Resources

Solution:

Salt, Gold and Copper are three common minerals used everyday

Solution:

Rocks from which minerals are obtained are known as ores. For any material to be called ore of any mineral, it must contain minimum adequate quantity of that mineralso that it can be extracted profitably.

Solution:

Russia and Norway are the two regions rich in natural gas resources.

Solution:

(a) Biogas energy for ruralareas

(b) Hydel and tidal energy for coastal areas

(c) Wind and solar energy for arid regions

Solution:

Five ways in which energy can be saved at home:

(i) Switching off lights, fns: and other electrical appliances when not in use

(ii) By seeing to it that electrical devices are operating efficiently; for example, defrosting refrigerator regularly and not keeping the refrigerator door open for longer than necessary

(iii) Using energy-efficient devicessuch asfluorescent bulbs and tubes

(iv) Using energy efficiently while cooking; for example, keeping the lids close, while cooking

(v) Unplugging electrical devices when not in use prevents leakage of electricity; thus saving energy.

Question 1: Which one of the following is NOT a characteristic of minerals?

(a) They are created by natural processes.

(b) They have a definite chemical composition.

(c) They are inexhaustible.

(d) Their distribution is uneven.

Solution:

(c) They are inexhaustible.

Question 2: Which one of the following is NOT a producer of mica?

(a) Jharkhand

(c) Rajasthan

(b) Karnataka

(d) Andhra Pradesh

Solution:

(b)Karnataka

Question 3: Which one of the following is a leading producer of copper in the world?

(a) Bolivia (c) Chile (b) Ghana (d) Zimbabwe

Solution:

(c) Chile.

Question 4: Which one of the following practices will NOT conserve LPG in your kitchen.

(a) Soaking the dal for some time before cooking it.

(b) Cooking food in a pressure cooker.

(c) Keeping the vegetables chopped before lighting the gas for cooking.

(d) Cooking food in an open pan kept on low flame.

Solution:

(d) Cooking food in an open pan kept on low flame.

Solution:

Environmental aspects must be carefully looked into before building huge dams because of the following reasons –

(i) Dams create imbalance in the earth’s equilibrium.

(ii) Deforestation leadsto environmental pollution.

(iii) People become displaced.

(iv) Cities / villages / towns may require shifting causing lot of hardships for the people. (v) Flood threatsloom large.

(vi) Earthquake threats

(vii) Silting of lakesis a problem

Solution:

Coal is used as a source of energy and power and also as a raw material in most of the industries. Hence most industries are concentrated around coal mines of the purpose saving cost of transportation of coal (cost effectiveness).

Solution:

Petroleum is referred to as “black gold” because it is black in colour in the crude form and its derivatives are extremely valuable as petroleum itself. Today it is almost inevitable in our day-to-day life. A variety of products like – kerosene, diesel, petrol, wax, plastics, lubricants etc. are produced from these mineral resources.

Solution:

Quarrying can become a major environmental concern because of the following reasons:

(i) It may destroy the humus of soil which is much required for the growth of plants and crops.

(ii) It produces a lot of noise pollution due to use of explosives at times in order to break the huge chunks of rocks.

(iii) In the process of quarrying lot of dust is generated which causes air pollution and also occupational hazards.

(iv) Blasting done in the process of quarrying generate vibration which damage in the nearby buildings, dams or any other similar structure.