Question. 1. Differentiate between a rock and an ore.
Answer. A rock is an aggregate of one or more minerals. An ore is a rock from which minerals are mined.
Question.2. Define quarrying.
Answer. Quarrying is a process of extraction in which minerals lying near the surface are simply dug out.
Question.3. Name the leading tin producers in Asia.
Answer. China, Malaysia and Indonesia are leading tin producers in Asia.
Question.4. Name two areas in Australia, which have large deposits of gold.
Answer. Two areas in Western Australia having large deposits of gold are Kalgoorlie and Coolgardie.
Question.5. Name two minerals in whose production India contributes a significant part.
Answer. India has vast deposits of high grade iron ore, and it is also a leading producer of salt.
Question.6. In which industry is silicon important? From which ore is it obtained?
Answer. Silicon is important in the computer industry. It is obtained from quartz.
Question.7. Why are minerals considered non-renewable?
Answer. Minerals take thousands of years to form. The rate of formation is much smaller than rate of consumption. So we classify them as non-renewable.
Question..8. Why is coal called “buried sunshine”?
Answer. Coal is called “buried sunshine” because it is found buried under the earth, and is as important a source of energy as sunshine.
Question.9. Why are petroleum and its derivatives called “black gold”?
Answer. Petroleum and its derivatives are black in colour but as valuable as gold, so we refer to it as “black gold”.
Question.10. What is natural gas?
Answer. Natural gas is a fossil fuel obtained with petroleum deposits in oil fields.
Question.11. Which was the first country to develop hydroelectricity ?
Answer. Norway was the first country to develop hydroelectricity.
Question.12 .Name some important hydel power stations in India.
Answer. Bhakra Nangal, Gandhi Sagar, Nagaijunasagar and Damodar Valley Projects are important hydel power stations in India.
Question.13. Name nuclear power stations in India.
Answer. Kalpakkam, Tarapur, Ranapratap Sagar, Narora and Kaiga are the nuclear power stations in India.
Question.14. Give one advantage of biogas over natural gas.
Answer. Biogas is a renewable source of energy whereas the amount of natural gas is limited.
SHORT ANSWER TYPE QUESTIONS
Question.1. Name and describe briefly methods of extraction.
Answer. Mining, drilling and quarrying are methods of extraction. Mining is a process of extraction of taking out minerals from rocks under the earth’s surface.
Open cast mining: In this, minerals lying at shallow depths are taken out by removing the surface layer.
Shaft mining: In this, deep bores (called shafts) are made to reach mineral deposits lying at large depths. Drilling: In this, deep wells are bored to take out minerals.
Quarrying: It is the process of extraction in which minerals lying veiy close to the surface are extracted just by digging them out.
Question.2. Where are minerals found?
Answer. Minerals are found in different types of rocks. Metallic minerals are usually found in igneous and metamorphic rocks that form large plateaus. Examples: iron ore is found in north Sweden, copper and nickel in Canada. In igneous and metamorphic rocks in South Africa, iron, nickel, chromites and platinum are found. Non-metallic minerals are found in sedimentary rock formations. Limestone deposits are found in France. Mineral fuels such as coal and petroleum are found in sedimentary strata.
Question.3. Describe the mineral distribution in North America.
Answer. The mineral deposits in North America are found in three zones: the Canadian region in the north of the Great Lakes, the Appalachian region and the Rocky Mountains in the West. Iron ore, nickel, gold, uranium and copper are mined in the Canadian Shield Region, coal in the Appalachian region. Western Cordilleras have vast deposits of copper, lead, zinc, gold and silver.
Question.4. Write common uses of minerals.
Answer. Minerals are important in many industries. Minerals used in gems are usually very hard. These are then set in varying styles of jewellery. Iron and copper are metals used in almost everything. Copper is present in everything from coins to pipes and electricity wires. Silicon, obtained from the mineral quartz, is the base of computer industry. Aluminium, obtained from bauxite ore, and its alloys are used in aeroplanes due to their light weight. Aluminium is also used in kitchen cookware.
Question.5. How is hydroelectricity, produced?
Answer. Hydroelectricity is produced from the energy possessed by water falling from great heights. River water is stored in dams. When rain water or river water falls from heights, it flows over turbine blades placed at the bottom of the dam. The moving blades are connected to a generator which produces electricity from this energy. This electricity is called hydroelectricity. The water discharged after its production is used for irrigation.
LONG ANSWER TYPE QUESTIONS
Question. 1. Name and describe some non- conventional sources of energy.
Answer. Non-conventional power sources are those power sources that have come into use recently due to the depleting conventional resources and growing awareness. Solar energy, wind energy, geothermal energy, nuclear power and tidal energy are examples of non- conventional power sources.
Solar energy is the heat and light energy captured from the sun. Solar cells help to convert this energy to electricity. Solar energy is used in solar heaters, solar cookers, solar dryers, etc.
Wind energy is the energy possessed by moving air (wind). Windmills are used to convert wind energy to electricity. Wind farms having clusters of windmills located in coastal regions and mountain passes.
Nuclear power is energy possessed by the nuclei of atoms of naturally occurring radioactive elements like uranium-, thorium, etc.
Geothermal energy is the heat energy obtained from the inside of the earth. The temperature inside the earth increases as we go deeper. This heat is used to produce electricity. It is accessed in the form of hot springs. Tidal energy is the energy generated from tides. It is harnessed by building dams at narrow openings of the sea. 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.2. Write the advantages and dis¬advantages of non-conventional sources of energy.
- Non-conventional sources of energy are usually inexhaustible. They do not pollute the environment.
- Nuclear power is emitted in large amounts.
- Most non-conventional sources of energy cost less.
- These forms of energy are safe to use and clean.
- 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.
- Setting up windmills disturbs radio and TV broadcast.
- Harnessing tidal energy destroys natural habitats of wildlife.
- Moreover, tidal energy is difficult to harness.
- Obtaining nuclear energy from radioactive material generates radioactive waste. It is expensive too.
- Biogas, although useful and renew¬able, contributes to greenhouse effect.