Mineral and Power Resources Geography SST NCERT Class 8 Extra Questions

Question 1
What is a mineral?
Solution :
Minerals are found in the earth and are naturally occurring substances. They are not made by man. They are found in rocks and water. They are chemical substances and are made of elements.
Question 2
What are the classifications of minerals?
Solution :
Minerals can be classified as Metallic and Non – metallic minerals. Metallic minerals are further divided into Ferrous and non-ferrous minerals.
Question 3
How are mineral extracted from earth?
Solution :
Minerals can be extracted by Mining; Drilling and Quarrying.
Question 4
Give a brief note on mining.
Solution :
The process of taking out minerals from rocks buried under the earth’s surface is called mining. Mining can be classified into Open-cast mining and shaft mining.
Open-cast mining, refers to a method of extracting rock or minerals from the earth by their removal from an open pit or borrow. Open-pit mines are used when deposits of commercially useful minerals or rock are found near the surface.
Shaft mining refers to the method of sinking a vertical or near-vertical tunnel from the top down, where there is initially no access to the bottom. The shafts have to be made to reach mineral deposits that lie at great depths.
Question 5
Name the different rocks that minerals occur in?
Solution :
Minerals occur in different types of rocks. They are Igneous rocks; Metamorphic rocks and Sedimentary rocks.
Question 6
Write a brief note on salt.
Solution :
Salt is a dietary mineral essential for animal life. It is composed primarily of sodium chloride. Salt is produced in different forms; they are unrefined salt or sea salt, refined salt or table salt and iodized salt.
Salt is a crystalline solid, white, pale pink or light grey in color. It is obtained by evaporation of sea water, usually in shallow basins warmed by sunlight.
It is also obtained from rock deposits.
Salt is used in more than 14,000 commercial applications other than in cooking. It is used in the manufacture of pulp and paper and setting dyes in textiles and fabric. It is also used in producing soaps and detergents and for making snow-covered roads safe in winter.
Salt plays an essential role in our daily lives.
Question 7
Mention a few minerals and their uses.
Solution :
Gold, silver and platinum are used in the jewellery industry.
Copper is used in the coin industry and for making pipes and wires.
Silicon obtained from quartz is used in the computer industry.
Aluminium obtained from bauxite ore is used in automobiles and airplanes, bottling industry, buildings and even in kitchen cookware.
Question 8
What do the 3Rs stand for in context with conservation of natural resources?
Solution :
The 3Rs stand for, reduce; reuse and recycle.

• Reduce – to use less
• Reuse – to put again into service without changing
• Recycle – to put again into service with changing

Question 9
What are the two main classifications of power resources?
Solution:
Power resources can be classified into conventional sources and non-conventional sources of power.

Question 10
What is Hydel power?
Solution :
When power is generated from the force of moving water it is called Hydel power. Rainwater or river water is stored in dams and made to fall from heights. The falling water flows through pipes inside the dam over turbine blades placed at the bottom of the dam. The moving blades then turn the generator to produce electricity.
The water discharged after the generation of electricity is used for irrigation. One fourth of the world’s electricity is produced by Hydel power.

Question 11
What is wind power?
Solution:
Wind power is the fastest-growing energy source in the world. A wind turbine works the opposite of a fan. Instead of using electricity to make wind, a turbine uses wind to make electricity. The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity. The electricity is sent through transmission and distribution lines to a substation, then on to homes, business houses and schools.

Question 12
What is biogas?
Solution:
Organic waste such as dead plant and animal material, animal dung and kitchen waste can be converted into a gaseous fuel called biogas. Biogas is essentially a mixture of methane and carbon dioxide. The organic waste is decomposed by bacteria in biogas digesters to emit biogas. Biogas is an excellent fuel for cooking and lighting. Biogas plants produce huge amounts of valuable organic manure each year.