Topic outline

    • Mineral and Power Resources

      Q70. What are the advantages and disadvantages of firewood?

      Ans. Advantages

                              i.        Easy access.

                             ii.        Provides energy to large number of people.


                              i.        Collection is time consuming.

                             ii.        Polluting.

                            iii.        Promoting greenhouse effect.

                            iv.        Deforestation.


      Q71. What are the advantages and disadvantages of wind energy?

      Ans. Advantages

                               i.        Non-Polluting.

                              ii.        Low cost production of electricity once setup.

                             iii.        Safe and clean.


                               i.        Noise pollution.

                              ii.        Wind mills costly to setup.

                             iii.        Disturbs T.V and radio reception.

                             iv.        Harmful to birds.

      Q72. Give five ways in which you can save energy at home.

      Ans. Five ways in which one can save energy at home:

                              i.        Using solar energy as much as possible.

                             ii.        Drying clothes in sunlight instead of electric dryers to prevent unnecessary use of electricity.

                            iii.        Switching off lights, fans and other electrical appliances when not in use.

                            iv.        Using energy efficient devices such as florescent bulbs and tubes.

                             v.        Using pressure cookers for cooking.


      Q73. Distinguish between Conventional and non-conventional sources of energy.

      Ans. Difference between Conventional and non-conventional sources of energy

      Conventional energy

      Non-conventional energy

      1. Conventional sources of energy are those which have been in common use for a long time.

      1. Non-conventional sources of energy are those which have been identified few decades ago.

      2. They are generally exhaustible.

      2. They are generally in exhaustible.

      3. They pollute environment, on a large scale and adds to global warming.

      3. They are environment friendly sources, which does not cause pollution.

      4. Example: Firewood and fossil fuels

      4. Example: solar energy, wind energy and  tidal energy

      Q74. Distinguish between Biogas and natural gas.

      Ans. Difference between biogas and natural gas.


      Natural gas

      1. It is produced using organic waste such as dead plant and animal material, animal dung and kitchen waste.

      1. Natural gas is found with petroleum deposits and is released when crude oil is brought to the surface.

      2. It can be used for cooking and lighting.

      2. It can be used as a domestic and industrial fuel.

      3. It is non-conventional source of energy.

      3. It is a conventional source of energy.

      4. It is renewable source of energy.

      4. It is non-renewable source of energy.


      Q75. Name and describe briefly methods of extraction.
      What are the different methods of mineral extraction?
      How are minerals extracted from the Earth?
      Give a brief note on mining.

      Ans.  Mining - The process of taking out minerals from rocks buried under the earth’s surface is called mining.

      Open-cast mining - Minerals that lie at shallow depths are taken out by removing the surface layer; this is known as open-cast mining.

      Shaft mining - Deep bores, called shafts, have to be made to reach mineral deposits that lie at great depths. This is called shaft mining.

      Drilling - Petroleum and natural gas occur far below the earth’s surface. Deep wells are bored to take them out, this is called drilling.

      Quarrying - Minerals that lie near the surface are simply dug out, by the process known as quarrying.

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