These DAV Class 8 SST Book Solutions and DAV Class 8 SST Chapter 4 Question Answer – Mineral and Energy Resources are thoughtfully prepared by experienced teachers.
DAV Class 8 SST Ch 4 Question Answer – Mineral and Energy Resources
DAV Class 8 SST Ch 4 Solutions – Mineral and Energy Resources
Something to Know
A. Tick (✓) the correct option.
Question 1.
Which one of the following is not a characteristic of rocks?
(a) These are composed of mineral ciystals.
(b) These have a definite mineral composition.
(c) These vary in harness and colour.
(d) These form outermost shell of the earth.
Answer:
(b) These have a definite mineral composition.
Question 2.
Which one of the following is the best quality of coal?
(a) lignite
(b) bituminous
(c) anthracite
(d) peat
Answer:
(c) anthracite
Question 3.
The major oilfields of India are located in which one of the following states of India?
(a) Assam
(b) Rajasthan
(c) Bihar
(d) Tamil Nadu
Answer:
(a) Assam
Question 4.
The metallic minerals used in electrical industry are-
(a) copper and bauxite
(b) iron and copper
(c) mica and manganese
(d) bauxite and iron
Answer:
(b) iron and copper
Question 5.
Petroleum is not extracted from the oilfiels of North sea by-
(a) United Kingdom
(b) Denmark
(c) Norway
(d) Sweden
Answer:
(d) Sweden
B. Fill in the blanks.
Question 1.
A mineral is extracted from the region where its concentration is ________ .
Answer:
high
Question 2.
________ minerals are divided into ferrous and non-ferrous.
Answer:
Metallic
Question 3.
________ is obtained from bauxite ore.
Answer:
aluminium
Question 4.
Petroleum, coal, ________ and hydroelectricity are conventional sources of energy.
Answer:
natural gas
Question 5.
________ and ________ are the major types of iron ore.
Answer:
Haemetite; magnetite
C. Write a technical term or an appropriate word for each of the following statements.
1. Energy generated by turbines run by water falling from a height.
Answer:
Hydel power
2. The resultant metal with improved strength which is produced by mixing two or more than two metals.
Answer:
Alloy
3. Materials formed inside the earth by the decompostion of dead remains of plants and animals in sedimentary rocks.
Answer:
Fossil fuels
4. Mineral deposits that are formed when a river erodes rock constituents from a primary source and deposits them in the river beds.
Answer:
Placer deposits
5. The process of extracting minerals from the earth’s crust.
Answer:
Mining
D. Answer the following questions in brief.
Question 1.
What is mineral? Mention the three main processes of mineral extraction.
Answer:
All rocks contain crystals of naturally occuring chemicals called minerals.
Question 2.
What is tidal energy? How can it be harnessed?
Answer:
Energy generated from tides is called tidal energy. It can be harnessed by building dams at narrow openings of the sea.
Question 3.
Why do we need to conserve mineral resources? Explain any three reasons.
Answer:
We need to conserve mineral resources because of the following reasons:
- Minerals are exhaustible resources. These resources are limited and unevenly distributed.
- Per head consumption of minerals is higher in developed countries as compared to the developing countries.
- Industry and agriculture strongly depend upon mineral deposits and the substances manufactured from them.
- We are rapidly consuming mineral resources that required millions of years to be created and concentrated.
- 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.
Question 4.
What are two types of energy sources? Which one of them is a better resource and why?
Answer:
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.
Question 5.
Highlight any three advantages of using nuclear energy.
Answer:
- Nuclear energy is veiy powerful and efficient resource than other alternative energy sources.
- It is an alternative to fossil fuels and can reduce the emission of the greenhouse gases.
- The cost of nuclear fuel (overall uranium) is 20 per cent of the cost of energy generated.
E. Answer the following questions.
Question 1.
How are minerals useful to us? Explain with the help of examples.
Answer:
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 which 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 airplanes, bottling industry, buildings and even in kitchen cookware.
Question 2.
In your opinion, electricity is a boon or a bane? Support your answer with relevant arguments.
Answer:
People use electricity for lighting, heating, cooling and operating k appliances, computers, electronic, machinery and vehicles. The water discharged after the generation of 1 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.
Question 3.
What is meant by nuclear energy? Explain the progress made by India in this field.
Answer:
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.
Question 4.
Assess the importance of petroleum on the basis of its wide range of applications.
Answer:
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.
Question 5.
Suggest any five measures to conserve minerals and energy resources.
Answer:
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:
- Use of non-conventional sources of energy, i.e., solar light, solar torch, solar geyser, etc.
- Use of CFL bulbs and tubelights.
- Switch off the light and fans when not in use.
- Dry clothes in sunlight instead of electric diyers to prevent emissions and unnecessary use of electricity.
- Use public transport.
- Use of automatic electronic power saver. It saves approximately 30% electricity bill.
Value Based Question
As we become more and more familiar with the harmful effects of burning fossil fuels, we need to look for alternatives. Nuclear energy is one such example. It rs a carbon free energy source and can provide a major solution to global warming and energy security. Nuclear energy is much more proficient than other energy resources.
However, the development and use of nuclear energy has its flaws also. The potential for severe harm caused by nuclear energy to human communities and future generations is too great a threat to our collective survival.
Question 1.
How far is nuclear energy really a viable source of energy?
Answer:
Nuclear energy is a carbon free energy source and can provide an important solution to global warming and energy security. It does not pollute the environment, if managed properly.
Question 2.
How can technological advancements fulfil the increasing demand for energy sources? Give examples to substantiate your answer.
Answer:
Technological advancement can fulfill the increasing demand for energy sources. For example,
(i) Petroleum is derived from organic materials trapped in sediments as they were deposited on the seabed. It serves as a transport fuel, lubricant and a raw material for a variety for products. Crude petroleum is refined to yield petrol, diesel and kerosene in oil refineries. It is widely used to run machines, generate electricity and produce steam. Various by¬products like synthetic textiles, fertilisers, plastics, insecticides, rubber, drugs, wax, etc are obtained from it.
(ii) Natural gas is used as a transport fuel (CNG), domestic fuel (LPG) and for generating electricity. It is widely used as a raw material for manufacture of fertilisers.
(iii) Multi-purpose projects are large-scale hydro-projects often including dams for water retention, anals-irrigation, water processing and pipelines to water supply to cities and power generation.
(iv) Solar energy is tapped in many countries for domestic cooking and heating purposes.
(v) Biogas plants are quite common in India. Biogas is used for domestic consumption basically in rural areas.
Question 3.
Why should we discourage burning of fossil fuels? List any three reasons.
Answer:
(i) Fossil fuels like coal, wood, petroleum release unburnt carbon particles in the environment, which cause air pollution.
(ii) Burning of coal and diesel also releases sulphur dioxide gas. This gas is extremely suffocating. The oxides of nitrogen and sulphur get dissolved in rain and forms acids which is known as acid rain. This water is very harmful to plants, animals and historical monuments.
(iii) Burning of fossil fuels also releases a large amount of carbon dioxide into the atmosphere. Carbon dioxide is a greenhouse gas which is responsible for global warming.
Map Skill
Question 1.
Locate and label any four major nuclear power stations on an outline political map of India.
Answer:
Question 2.
On an outline political map of India, locate and label the leading states with respect to the reserves of:
(a) Iron ore (b) Bauxite (c) Coal (d) Petroleum
Answer:
Something to Do
Question 1.
Collect specimens of various minerals and display them in the science exhibition in your school.
Answer:
Do yourself.
Question 2.
Prepare a report on the hazards and environmental impact of mining in the coalfields, especially in the state of Jharkhand.
Answer:
Do yourself.
DAV Class 8 Social Science Chapter 4 Question Answer – Mineral and Energy Resources
A. Tick (✓) the correct option.
Question 1.
Iron ore and manganese ore are.
(a) ferrous minerals
(b) non-ferrous minerals
(c) minerals fuels
(d) energy resources
Answer:
(a) ferrous minerals
Question 2.
Steel is an alloy of iron and.
(a) manganese
(b) zinc
(c) tin
(d) silver
Answer:
(a) manganese
Question 3.
A mixture of copper and zinc is called
(a) steel
(b) bronze
(c) brass
(d) none of the above
Answer:
(d) none of the above
Question 4.
The mineral called the backbone of civilisation is
(a) bauxite
(b) copper
(c) petroleum
(d) iron
Answer:
(d) iron
Question 5.
Which one of the following groups can be categorised as gems?
(a) mica, gold, diamond
(b) sandstone, topaz, garnet
(c) diamond, topaz, garnet
(d) diamond, topaz, sulphur
Answer:
(c) diamond, topaz, garnet
Question 6.
Large reserves of iron are found in
(a) Odisha
(b) Karnataka
(c) Chhattishgarh
(d) All of the above
Answer:
(d) All of the above
Question 7.
One of the following states which does not produce mica is
(a) Andhra Pradesh
(b) Chhattisgarh
(c) Bihar
(d) Jharkhand
Answer:
(b) Chhattisgarh
Question 8.
A leading producer of copper in the world is
(a) Austria
(b) Canada
(c) France
(d) Sweden
Answer:
(a) Austria
Question 9.
Kolar mines in Karnataka is famous for large deposits of
(a) iron ore
(b) gold
(c) bauxite
(d) manganese
Answer:
(b) gold
Question 10.
Which of the following is not a conventional sources of energy?
(a) Coal
(b) Petroleum
(c) Natural gas
(d) Biogas
Answer:
(d) Biogas
Question 11.
contains about 90% carbon and emits little smoke
(a) Anthracite
(b) Bistuminous
(c) Lignite
(d) Peat
Answer:
(a) Anthracite
Question 12.
About 60% of the petroleum is obtained from the
(a) Off-shore regions of Gujarat
(b) Countries around North Sea
(c) Middle East
(d) Caspian Sea
Answer:
(c) Middle East
Question 13.
The leading producers of hydel power in the world are
(a) Brazil, Canada and Denmark
(b) Brazil, Canada and Denmark
(c) Norway, Russia and China
(d) Algeria, Argentina and Bolivia
Answer:
(a) Brazil, Canada and Denmark
Question 14.
The largest solar plant in India is located in
(a) Rajasthan
(b) Punjab
(c) Bihar
(d) Gujarat
Answer:
(d) Gujarat
Question 15.
In India, Manikaram in Himachal Pradesh is famous for generating
(a) wind energy
(b) tidal energy
(c) geothermal energy
(d) nuclear energy
Answer:
(c) geothermal energy
Question 16.
Which one of the following non- conventional sources of energy is commonly used in rural areas?
(a) Wind energy
(b) Solar energy
(c) Nuclear energy
(d) Biogas
Answer:
(d) Biogas
B. Write a technical term or an appropriate word for each of the following statements.
1. Earth’s materials, which do not have definite chemical composition and can be hard or soft.
Answer:
Rock
2. Hard substances with a shine and lustre are extracted from the earth.
Answer:
Metallic numerals
3. Deposits that are formed when a river erodes minerals from one region and deposits them in the river beds.
Answer:
Placer deposits
4. It is the hardest, brightest and best quality of coal.
Answer:
Anthracite
B. Very Short Answer Type Questions
Question 1.
What is an alloy?
Answer:
Sometimes two or more metals are mixed to improve the strength of a metal. This is called an alloy.
Question 2.
Mention the various uses of aluminium.
Answer:
Aluminium is used in the manufacturing of electric wires, aeroplanes, spare parts of vehicles, pipes, the construction of stairs, window frames, shutters, utensils and other household goods.
Question 3.
Name different types of coal.
Answer:
Different types of coal are:
(i) Anthracite
(ii) Bituminous
(iii) Ligmote
(iv) Peat
Question 4.
State the importance of nuclear energy.
Answer:
Nuclear energy is used for household and industrial purposes.
Question 5.
What is energy crisis?
Answer:
Scarcity of conventional resources of energy is referred to as energy crisis.
Question 6.
What is rock? Give some examples of rocks.
Answer:
Rock is a mixture of one or more minerals. Sandstone, limestone, basalt and granite are some examples of rocks.
Question 7.
What is called ore? Give example.
Answer:
A rock having large concentration of a particular metal is called its ore. For example, iron ore, magnese ore etc.
Question 8.
What information does Geological Survey of India provide?
Answer:
Geological Survey of India provide information about earth science to the government, industry and public in general.
Question 9.
What is the condition for extraction of minerals from mines?
Answer:
Minerals are extracted from mines only if the concentration of a particular mineral is high and it is commercially able and useful.
Question 10.
What is the characteristic feature of metallic minerals?
Answer:
Metallic minerals are hard substances with a shine or lustre. Metal obtained from its ore can be moulded into any shape.
Question 11.
Give two examples of non-ferrous minerals.
Answer:
Gold and silver are examples of non- ferrous minerals.
Question 12.
Give two examples of ferrous minerals.
Answer:
Iron ore and manganese ore are examples of ferrous minerals.
Question 13.
Name two mineral fuels.
Answer:
Coal and petroleum.
Question 14.
What are mineral fuels?
Answer:
Mineral fuels are used as sources of energy. They are obtained from sedimentary rocks. These consist of coal (Solid), petroleum (liquid) and natural gas (gaseous).
Question 15.
Write two uses of iron.
Answer:
(i) Iron is used for manufacturing machines.
(ii) It is used for constructing buildings.
Question 16.
Name the leading producers of bauxite in the world.
Answer:
Australia, Brazil, Guinea and Jamaica.
Question 17.
Mention various uses of copper.
Answer:
Copper is widely used in electric goods, such as generators wireless system, electric motors, radio, telephone, electric wires, refrigerators, utensils, etc.
Question 18.
Name the major bauxite-producing states of India.
Answer:
Odisha, Gujarat, Jharkhand and Maharashtra.
Question 19.
What are the three ways to generate electricity?
Answer:
The three ways to generate electricity are thermal power plants, nuclear power plants and hydroelectric power plants.
Question 20.
What is the function of grid?
Answer:
Grid maintains the distribution of energy in the surrounding regions.
Question 21.
Name the two developed countries where consumption of electricity is quite high.
Answer:
Japan and America.
Question 22.
How is most of the energy of the world produced?
Answer:
Most of the energy of the world is produced by using coal, mineral oil and natural gas.
Question 23.
How is Anthracite the best quality of coal?
Answer:
Anthracite contains about 90% carbon and emit little smoke.
Question 24.
Mention two uses of coal.
Answer:
(i) Coal is widely used in iron and steel industry and thermal power stations.
(ii) It is also used as a raw material in various chemical industries.
Question 25.
Why petroleum and its derivatives called black gold?
Answer:
Petroleum and its derivatives are called black gold because they are valuable.
Question 26.
Where are reserves of petroleum found in India?
Answer:
In India, reserves of petroleum are found in Assam, Gujarat and Maharashtra. It is also found in the delta regions of Godavari and Krishna.
Question 27.
Mention the uses of natural gas. How is it transported throughout the world?
Answer:
Natural gas is widely used to run vehicles as CNG (Compressed Natural Gas). Throughout the world, it is transported through pipelines over great distances.
Question 28.
What is the use of the water discharged after the generation of electricity?
Answer:
The water discharged after the generation of electricity is used for irrigation.
Question 29.
Name any two multipurpose projects that have been established in India for generating electricity.
Answer:
(i) Bhakra Nangal dam.
(ii) Nagarjuna Sagar dam.
Question 30.
What are the various uses of solar energy.
Answer:
Solar energy is used for a number of purposes, such as solar cookers, solar gysers, solar cars, solar dryers, solar lanterns, solar street lighting system, etc.
Question 31.
How is nuclear energy obtained?
Answer:
Nuclear energy is obtained from energy stored in number of dams of naturally occurring radioactive elements like uranium and thorium.
Question 32.
What is called tidal energy?
Answer:
Energy generated from tides is called tidal energy.
Question 33.
How can tidal energy be harnessed?
Answer:
Tidal energy can be harnessed by building dams at narrow openings of the sea.
Question 34.
Where are huge tidal mill farms located in India?
Answer:
In India, huge tidal smill farms are located in the Gulf of Kachchh.
Question 35.
Mention two uses of biogas.
Answer:
(i) Biogas is an excellent fuel for cooling and lighting.
(ii) It produces huge amount of organic manure.
C. Short Answer Type Questions
Question 1.
Distinguish between rocks and minerals
Answer:
| Rocks | Minerals |
| (i) Rocks do not have definite chemical composition. | (i) They are uniform in structure and composition. |
| (ii) Rocks can be hard or soft. | (ii) They are obtained from rocks having one or more minerals. |
| Examples: Sandstone, Lime, Basalt, Granite etc. | Examples: Coal, Petroleum, Iron, Bauxite, Copper etc. |
Question 2.
Differentiate between Thermal energy and Solar energy.
Answer:
| Thermal energy | Solar energy |
| (i) It is generated by using coal, petroleum and natural gas. | (i) Sun is the greatest source of this energy. |
| (ii) It causes pollution. | (ii) It does not cause pollution. |
| (iii) The thermal power stations use non-renewable fossil fuels for generating electricity. | (iii) Solar photovoltaic (SPV) converts sunlight directly into electricity. |
Question 3.
What are metallic minerals? Mention their two categories.
Answer:
Metallic minerals are hard substances with a shine or lustre. Metal obtained from its ore can be moulded into any shape. Metallic minerals can be sub¬divided into two categories:
(i) Ferrous: These minerals contain iron and include iron ore and manganese ore.
(ii) Non-ferrous: These minerals contain metals other than iron. They include ores of gold and silver.
Question 4.
What is an alloy? Give three examples? How are they obtained?
Answer:
Sometimes two or more metals are mined to improve the strength of a metal. This is called on alloy.
Examples:
(i) Brass is an alloy obtained by a mixture of copper and zinc.
(ii) Bronze is an alloy of copper and tin.
(iii) Steel is an alloy of iron and manganese.
Question 5.
The distribution of mineral resources is highly uneven in the world.’ Support with three arguments.
Answer:
- The distribution of minerals depends on the life of rocks available in a region. Igneous and metamorphic rocks are rich in minerals like iron ore, manganese ore, gold, silver, lead, etc.
- Mineral fuels are restricted to sedimentary rocks.
- Sometimes agents of gradation, such as rivers erode minerals from one region and deposit them somewhere else in the river beds. These are called placer deposits.
Question 6.
(i) What are the various use of iron?
(ii) How can you say that the distribution of iron ore in the world is uneven?
Answer:
(i) Iron is used for manufacturing machines, automobiles, rail tracks, electric poles, constructing buildings, bridges, ship-building, weapons, agricultural implements and articles of general use.
(ii) About 90% reserves of iron ore are found in ten countries. They include Brazil, Canada, China, France, India, Russia, Sweden, United Kingdom, USA and Venezuela. It is also found in Australia, Germany, Kazakhastan, South Africa and Ukraine.
Question 7.
What does the conservation of minerals imply? Mention three measures to conserve minerals.
Answer:
The conservation of minerals does not mean preservation of minerals. It implies that efforts should be made to utilize minerals in the best possible way, depending upon the industrial need and changing technological requirements.
Three measures to conserve minerals:
- Use of efficient methods of mining and processing which would save the wastage.
- Recycling of mineral resources use and reuse of scrap (metallic waste).
- Substituting the use of scarce minerals by those found in abundance.
Question 8.
Mention different ways of electricity generation. How is electricity transmitted after generation?
Answer:
Different ways of electricity generation:
(i) Electricity is generated through thermal power plants, nuclear power plants and hydroelectric power plants.
(ii) It is also produced through non- conventional sources of energy, such as tidal energy, solar energy, wind energy and geothermal energy.
After generation, electricity is transmitted to the grid through wires. Grid maintains the distribution of energy in the surrounding regions.
Question 9.
What are the various uses of petroleum or mineral oil?
Answer:
- Petroleum or mineral oil is widely used as a source of power. Patrol, diesel and kerosene oil are the by products of petroleum/mineral oil.
- As an industrial power, it is widely used to run machines, to 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 in petro-chemical industries for preparing rubber, synthetic fibres, etc.
Question 10.
Write a brief note on hydel power.
Or
How is hydro-electricity produced? Name the leading produces of hydel power in the world.
Answer:
Rain water or river water stored in dams is made to fall from height. 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 which is known as hydro-electricity. The leading produces of hydel power in the world are Brazil, Norway and Paraguay.
Question 11.
What are the three conditions for generating hydro-electricity?
Answer:
(i) For generating hydro-electricity, large dams are required.
(ii) Hilly regions with perennial rivers are ideal from it.
(iii) In the initial stage, it requires high technology and huge capital investment.
D. Long Answer Type Questions
Question 1.
Distinguish between biogas and natural gas.
Answer:
| Biogas | Natural gas |
| (i) It is obtained from the decomposition of organic waste. | (i) It is obtained as a by product from the extraction of petroleum. |
| (ii) It is a renewable source of energy. | (ii) It is a non-renewable source of energy. |
| (iii) It is an excellent fuel for cooking and lighting and produces huge amounts of organic manure. | (iii) It is widely used to run vehicles as CNG (Compressed Natural Gas). |
| (iv) It is a non-conventional source of energy. | (iv) It is a conventional source of energy. |
Question 2.
Why is conservation of energy resources essential? Give three reasons.
Answer:
- Conservation of energy resources is essential because of the rapid depletion and very slow regeneration of the exhaustible sources of energy, i. e., coal, petroleum and natural gas.
- Population is growing very fast. As a result, consumption of energy resources has increased manifolds.
- The fossil fuels are non-renewable in nature. Rampant exploitation of non-renewable resources like coal, and petroleum can lead to energy crises.
- The rate of consumption of energy sources is more than the rate of their formation.
Question 3.
Mention the distribution of petroleum in the World.
Answer:
(i) About 60% of the petroleum is obtained from the Middle East. Regions around Black Sea, Caspion Sea, Persion Gulf and Red Sea have the largest reserves of petroleum of the world. It is mainly obtained from south-west Asian countries.
(ii) Petroleum is also found in Algeria, Aragentina, Bolivia, Brazil, Canada, China, Columbia, India, Indonesia, Libya, Mexico, Nigeria, Russia, USA and Venezuela.
(iii) In India, the reserves of petroleum are found in Assam, Gujarat and Maharashtra. It is also found in the delta regions of Godavari and Krishna.
Question 4.
Conventional and non-conventional resources of energy.
Answer:
| Conventional sources | Non-conventional sources |
| (i) Traditional sources, e.g. coal, petroleum, natural gas. | (i) These are still at experimental stage. Non-traditional, e.g. solar energy, wind energy, geothermal energy. |
| (ii) They are expensive. | (ii) They are inexpensive. |
| (iii) They have unfavourable impact on environment as they cause pollution. | (iii) They do not create bad impact on environment and thus, are eco-friendly. |
| (iv) At present, there is a lot of dependency on them. | (iv) In future,the dependency on these resources will increase. |
Question 5.
Solar energy is fuel of future. ’ Explain it with suitable arguments.
Answer:
(i) Sun is the greatest source of unlimited energy. Specially in the tropical zone, it can be tapped to get maximum output. Photovoltaic technology converts sunlight directly into electricity.
(ii) Solar energy is fast becoming popular in rural and remote areas.
(iii) It is expected that use of solar energy will be able to minimise the dependence of rural households on firewoods and dung cakes, which in turn will contribute to environmental conservation and adequate supply of manure in agriculture.
(iv) Solar energy is used for a number of purposes, such as solar cookers, solar geysers, solar cars, solar dryers, solar lanterns, solar street lighting system, etc.
Question 6.
What are the different types of minerals? Classify with the help of examples. Highlight the importance of minerals.
Answer:
Minerals are of different types. Generally, they are classified on the basis of their properties:
(i) Metallic minerals
(ii) Non-metallic minerals
(iii) Mineral fuels
(i) Metallic minerals are hard substances with a shine or lustre. They can be sub-divided into two categories:
- Ferrous containing iron. It includes iron ore and magnanese ore.
- Non-ferrous containing metals other than iron. It includes ores of gold and silver.
(ii) Non-metallic minerals do not contain metals and are lighter than metallic minerals. Generally, they contain:
- Building materials such as sandstone, limestone, granite, basalt, marble, etc.
- Gems such as diamond, topaz, garnet, etc.
- Others such as mica, sulpher, salt, etc.
(iii) Mineral fuels are obtained from sedimentaiy rocks. They consist of coal (solid), petroleum (liquid) and natural gas (gaseous).
Question 7.
Give an assessment of non- conventional sources of energy.
Or
What are the various non- conventional sources of energy? Describe them.
Answer:
Various non-conventional sources of energy are solar energy, wind energy, geothermal energy, nuclear energy, tidal energy and biogas.
(i) Solar energy: It is the heat and light energy, captured from the sun. Solar cells help to convert this energy to electricity. Nowadays, solar energy is used for a number of purposes, such as solar cookers, solar gysers, solar cars, solar dryers, etc. People are taking initiatives to make it more cost effective.
(ii) Wind energy: It is the energy possessed by moving air or wind. Wind mills are used to convert wind energy to electricity. Coastal areas are ideal for it. In India, Gujarat, Maharashtra and Tamil Nadu have a few wind mills.
(iii) Geothermal energy is the heat energy obtained from inside of the earth. The temperature inside the earth increases as we go deeper. This heat is used to produce electricity. It is more prominent in volcanically active areas, where frequency of hot springs, is high.
(iv) Nuclear energy is obtained from energy stored in nuclear of atoms of naturally occurring radioactive elements like uranium, thorium. It is used for household and industrial purposes.
(v) Tidal energy is generated from tides. This energy can be harnessed by building dams at narrow openings of the sea.
(vi) Biogas is a gaseous fuel obtained from the decomposition of organic waste like dead plant and animal material or animal dung and kitchen waste. It is an excellent fuel for cooking and lighting and is environment-friendly.
Question 8.
What are the advantages and disadvantages of non-conventional sources of energy?
Answer:
Advantages:
(i) Non-conventional sources of energy are usually inexhaustible. They do not pollute the environment.
(ii) Nuclear power is emitted in large amount.
(iii) Most non-conventional sources of energy cost less.
(iv) These forms of energy are safe to use and clean.
Disadvantages:
(i) Wind-mills are costly to set up. So, using them to harness wind energy is costly, even though the electricity generated from it is cheap.
(ii) Setting up windmills disturbs radio and TV broadcast.
(iii) Harnessing tidal energy destroys natural habitats of wildlife.
(iv) Obtaining nuclear energy from radioactive material generates radioactive waste. It is expensive too.
(v) Biogas, though useful and renewable, contributes to green house effect.
Question 9.
Give an assessment of the distribution of any five minerals in India.
Answer:
India is rich in having minerals like iron, bauxite, copper, mica, salt, etc.
(i) Iron: In India, high grade iron ore is produced in Jharkhand, Odisha, Chhattisgarh, Madhya Pradesh, Karnataka and Goa.
(ii) Bauxite: Bauxite is produced in Odisha, Jharkhand, Gujarat, Maharashtra, Chhattisgarh and Tamil Nadu.
(iii) Copper: It is mainly found in Madhya Pradesh, Rajasthan, Andhra Pradesh, Jharkhand and Karnataka.
(iv) Mica: Its deposits are found in states like Bihar, Jharkhand, Andhra Pradesh and Rajasthan. India is the largest producer and operator of mica in the World.
(v) Manganese: The main reserves of manganese ore are in states of Odisha, Madhya Pradesh, Karnataka, Andhra Pradesh, Chhattisgarh and Maharasthra.
Something to Do
Question 1.
Prepare a working model of a windmill.
Answer:
Do yourself.
Question 2.
Make a small model of a solar cooker and use it at home.
Answer:
For self-attempt.
Question 3.
Identify five articles in your house which are made up of various minerals or alloys.
Answer:
Glass, frying pan, plate, cup, gas- stove.
(a) Show the distribution of the following minerals on an outline map of India.
- iron ore
- bauxite
- coal
- petroleum
Answer:
For self-attempt
Question 4.
Mark the major mineral and coal reserves on an outline map of the world.
Answer:
For self-attempt