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DAV CLASS 8 Mineral and Energy Resources Social Science Question and Answers
Something to do.
A. Tick (√) the correct option .
1. Which one of the following is not a characteristic of rocks?
Ans 1. (b) These have a definite mineral composition.
2. Which one of the following is the best quality of coal?
Ans 2. (c) Anthracite
3. The major oilfields of India are located in which one of the following states of india?
Ans 3. (a) Assam
4. The metallic minerals used in electrical industry are –
Ans 4. (b) iron and Copper
5. Petroleum is not extracted from the oilfields of North Sea by
Ans 5. (d) Sweden
B. Fill in the blanks
1. A mineral is extracted from the region where its concentration is high.
2. Metallic minerals are divided into ferrous and non-ferrous.
3. Aluminium is obtained from bauxite ore.
4. Petroleum, coal, natural gas and hydroelectricity are conventional sources of energy.
5. Haematite and Magnetite are the major types of iron ore.
C. Write a technical term or an appropriate word for each of the following statement :
1. Energy generated by turbines run by water falling from a height.
Ans) Hydroelectric Power
2. The resultant metal with improved strength which is produced by mixing two or more than two metals.
3. Materials formed inside the earth by the decomposition of dead remains of plants and animals in sedimentary rocks.
Ans) Fossil Fuels
4. Mineral deposits are formed when a river erodes rock constituents from a primary source and deposits them in the river beds.
Ans) Placer deposits
5. The process of extracting minerals from the earth’s crust.
D. Answer the following questions in brief.
1. What is mineral? Mention the three main processes of mineral extraction.
Ans. All rocks contain crystals of naturally occuring chemicals called minerals.
2. What is tidal energy? How can it be harnessed?
Ans. Energy generated from tides is called tidal energy. It can be harnessed by building dams at narrow openings of the sea.
3. Why do we need to conserve mineral resources? Explain any three reasons.
Ans 3. We need to conserve mineral resources because of the following reasons: (i) Minerals are exhaustible resources. These resources are limited and unevenly distributed. (a) Per head consumption of minerals is higher in developed countries as compared to the developing countries. (iii) Industry and agriculture strongly depend upon mineral deposits and the substances manufactured from them. (iv) We are rapidly consuming mineral resources that required millions of years to be created and concentrated. (v) The geological processes of mineral extraction are so slow that the rates of replacement are infinitely small in comparison to the present rates of consumption.
4. What are two types of energy sources? Which one of them is a better resource and why?
Ans 4. Conventional and non-conventional are two types of energy sources. Non-conventional sources are better resources because they are renewable resources. They are less expensive to install and easy to maintain. These do source not cause air pollution and are largely eco-friendly.
5. Highlight any three advantages of using nuclear energy.
Ans 5. (i) Nuclear energy is very powerful and efficient resource than other alternative energy sources.
(ii) It is an alternative to fossil fuels and can reduce the emission of the greenhouse gases.
(iii) The cost of nuclear fuel (overall uranium) is 20 percent of the cost of energy generated.
E. Answer the following questions.
1. How are minerals useful to us? Explain with the help of examples.
Ans 1. In the modern world, minerals provide the basis for industrial development of a country. From the smallest objects like pins and nails to huge ships and aircraft, all are made of minerals. Minerals that are used for gems are usually hard. These are then set in various styles for jewellery. Copper is another metal used in everything from coins to pipes. Silicon, used in the computer industry is obtained from quartz. Aluminium obtained from its ore bauxite is used in automobiles and aeroplanes, bottling industry, buildings and even in kitchen cookware.
2. In your opinion, electricity is a boon or a bane? Support your answer with relevant arguments.
Ans 2. People use electricity for lighting, heating, cooling and operating appliances, computers, electronics, machinery and vehicles. The water discharged after the generation of electricity is used for irrigation. One-fourth of the world’s electricity is produced by hydel power. To generate hydroelectricity, large dams are needed. At the initial stage, it required high technology and huge capital investment. Resistance to large dams has been primarily due to the large-scale displacement of local communities. Local people often have to give up their land and livelihood.
3. What is meant by nuclear energy? Explain the progress made by India in this field.
Ans. Nuclear energy is obtained from power stored in the nuclei of atoms of naturally occurring radioactive elements like uranium and thorium. Major nuclear power stations in India are located at Kaiga in Karnataka, Kalpakkam and Kudunkulam in Tamil Nadu, Narora in U.P., Ranapratap Sagar near Kota in Rajashthan, Tarapur in Maharashtra and Kakrapar in Gujarat.
4. Assess the importance of petroleum on the basis of its wide range of applications.
Ans 4. Petroleum is widely used as a source of power. Petrol and kerosene oil are the by-products of Petroleum/ Mineral oil. As an industrial power, it is widely used to run machines, generate electricity and produce steam. Railway engines, motor vehicles and ships depend on it for their fuel requirements. It is used as a lubricant in machines and petrochemical industries for preparing rubber, synthetic, fibres, etc.
5. Suggest any five measures to conserve minerals and energy resources.
Ans 5. Following measures can be taken to conserve minerals:
• Many metals like iron, gold, silver and aluminium, once discarded, can be reused by recycling.
• Efficient methods of mining and smelting can avoid wastage of minerals. While using them also we should take care not to waste.
• Alternatives to minerals like biodegradable plastic, wood and other substitutes should be more widely used.
Following measures can be taken to conserve energy resources:
(i) Use of non-conventional sources of energy, i.e., solar light, solar torch, solar geyser, etc.
(ii) Use of CFL bulbs and tubelights.
(iii) Switch off the light and fans when not in use.
(iv) Dry clothes in sunlight instead of electric dryers to prevent emissions and unnecessary use of electricity.
(v) Use public transport.
(vi) Use of automatic electronic power saver. It saves approximately 30% electricity bill.