Class 8 Science NCERT Solutions for Chapter – 5 Coal and Petroleum

Coal and Petroleum

Question 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.

Question 2.
Name the petroleum product used for surfacing roads?

Answer:
These days bitumen, a petroleum product is used for surfacing the roads in place of coaltar.

Question 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.

Question 4.
Fill in the blanks.

(a) Fossil fuels are ______ , ______ and ______.
Answer:

  1. Coal
  2. Petroleum
  3. Natural gas

(b) Process of separation of different constituents from petroleum is called ______.
Answer:
Refining

(c) Least polluting fuel for vehicle is ______.
Answer:
CNG (compressed natural gas)

Question 5.
Tick True/False against the following statements:

(a) Fossil fuels can be made in the laboratory.
Answer:
False

(b) CNG is a more polluting fuel than petrol.
Answer:
False

(c) Coke is an almost pure form of carbon.
Answer:
True

(d) Coal tar is a mixture of various substances.
Answer:
True

(e) Kerosene is not a fossil fuel.
Answer:
False

Question 6.
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.

Question 7.
Describe the characteristics and uses of coke.

Answer:
Coke is a tough, porous, and black substance. It is an almost pure form of carbon. It is used in the manufacture of steel and in the extraction of many metals.

Question 8.
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.

Question 9.
The following table shows the total power shortage in India from 1991¬1997. Show the data in the form of a graph. Plot shortage percentage for the years on the Y-axis and the year on the X-axis.

S.No.YearShortage (%)
1.19917.9
2.19927.8
3.19938.3
4.19947.4
5.19957.1
6.19969.2
7.199711.5

Answer:
NCERT Solutions for Class 8 Science img 7

InText Questions and Answers

Activity 5.1

Question 1.
Make a list of various materials used by us in daily life and classify them as natural and man-made.

Answer:

NaturalMan-made
WaterPlastic
SunlightRubber
AirT.V.
SoilRefrigerator
CoalLassi
PetrolPen
LPGBed
CNGCar
MineralsBicycle
FruitsToffees

Question 2.
Does this list- include air, water, soil, and minerals?

Answer:
Yes, these are included in the list.

Question 3.
Can we use all our natural resources forever?

Answer:
Some natural resources are going to exhaust one day. So we cannot use them forever.

Question 4.
Can air, water, and soil be exhausted by human activities?

Answer:
No, these will not be exhausted by human activities.

Question 5.
Is water a limitless resource?

Answer:
Yes, water is a limitless source, but its unwise use and cutting of forest can also make its usable form scarce.

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