NCERT Class 8 Science Chapter 5 Coal and Petroleum

NCERT Solutions for Class 8 Science Chapter 5 Coal and Petroleum are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 5 Coal and Petroleum.

NCERT Class 8 Science Chapter 5 Coal and Petroleum

 

1. What are the advantages of using CNG and LPG as fuels?

Answer
  • The advantages of using CNG and LPG as fuels are as follows:
    1. These are clean fuels.
    2. These are low-cost fuels.
    3. These are available easily.
    4. These can be used directly for burning in homes and factories where it can be supplied through pipes.

     

    2. Name the petroleum product used for surfacing roads.

    Answer
  • A petroleum product ‘Bitumen’ is used for surfacing of roads.
  •  

    3. Describe how coal is formed from dead vegetation. What is this process called?

    Answer
  • About 300 million years ago, the earth was having dense forests in low-lying wetland areas. Due to earthquakes and volcanic eruptions, these forests got buried under the soil. As more soil deposited over them, they were compressed.
    The temperature also raised as they sank deeper and deeper. Due to high temperature and lack of oxygen, dead plants inside the earth got slowly converted to coal. As coal contains mainly carbon, the slow process of conversion of dead vegetation into coal is called carbonization.
  •  

    4. Fill in the blanks: (a) Fossil fuels are.…….,…………. and………..
    (b) Process of separation of different constituents from petroleum is called………………
    (c) Least polluting fuel for a vehicle is……………

    Answer
  • (a) coal, petroleum, natural gas
    (b) refining
    (c) CNG.
  •  

    5. Explain why fossil fuels are exhaustible natural resources.

    Answer
  • Fossil fuels are present in nature in limited quantity and are being exhausted abundantly by us. That is why fossil fuels are called exhaustible natural resources.
  •  

    6. Describe characteristics and uses of coke.

    Answer
  • Coke is a tough, porous, and black substance. It is an almost a pure form of carbon. “Coke is obtained by heating soft coal in the absence or little supply of air”.It is used in the manufacture of steel and in the extraction of many metals.
  •  

    7. Explain the process of the formation of petroleum.

    Answer
  • Petroleum is formed from organisms living in the sea. When these organisms died, their bodies settled at the bottom of the sea and got covered with layers of sand and clay. Over millions of years, they were transformed into petroleum and natural gas under the absence of air and the presence of high temperature and pressure
  •  

    8. Synthetic Fibres and Plastics.

    Answer
  • A synthetic fibre is a long chain of small units joined together, and each small unit is actually a chemical substance.
    • A polymer is a very big molecule formed by the combination of a large number of small molecules.
    •The word polymer comes from two Greek words poly meaning many and mer meaning units.
    •The small molecules which join to form a polymer are called monomers.
  •  

    9. Explain the process of the formation of petroleum.

    Answer
  • Petroleum is formed from organisms living in the sea. When these organisms died, their bodies settled at the bottom of the sea and got covered with layers of sand and clay. Over millions of years, they were transformed into petroleum and natural gas under the absence of air and the presence of high temperature and pressure
  •  

    10. Which of the following can be beaten into thin sheets?.

  • (a) Zinc
    (b) Phosphorus
    (c) Sulphur
    (d) Oxygen
    Answer >>
    (A) Zinc
  •  

    11. Which of the following statements is correct?.

  • (a) All metals are ductile.
    (b) All non-metals are ductile.
    (c) Generally, metals are ductile
    (d) Some non-metals are ductile
    Answer >>
    (C) Generally, metals are ductile
  •  

    12. Can you store the lemon pickle in an aluminium utensil? Explain.

    Answer >>
    Aluminium is a metal. Metals are more reactive to acids. That is why acidic foodstuffs like lemon pickles must not be stored in aluminium utensils

     

    13. One day Reeta went to a jeweller’s shop with her mother. Her mother gave old gold jewellery to the goldsmith to polish. The next day when they brought the jewellery back, they found that there was a slight loss in its weight. Can you suggest a reason for the loss in weight.

  • Answer >>
    In polishing, the jeweller put the gold jewellery in a mild acidic solution, which in reaction with acid goes into the solution. So, in this process, a certain amount of gold is lost to the acidic solution.
    We hope the NCERT Solutions for Class 8 Science Chapter 4 Materials: Metals and Non-Metals help you. If you have any query regarding NCERT Solutions for Class 8 Science Chapter 4 Materials: Metals and Non-Metals, drop a comment below and we will get back to you at the earliest
  •  

    12. Can you store the lemon pickle in an aluminium utensil? Explain.

  • Answer >>
    Aluminium is a metal. Metals are more reactive to acids. That is why acidic foodstuffs like lemon pickles must not be stored in aluminium utensils
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