CLASS 8 SCIENCE CHAPTER-5 COAL AND PETROLEUM

Question 1. What are the advantages of using CNG and LPG as fuels?
Solution : The advantages of using CNG and LPG as fuels are as follow:
1.CNG and LPG can be transported easily through pipe lines.
2.CNG and LPG burn easily.
3.CNG and LPG are clean fuels and they do not release smoke when burnt.
4.CNG and LPG give a lot of heat energy when burnt.

Question 2. Name the petroleum product used for surfacing of roads.
Solution : Bitumen.

Question 3. Describe how coal is formed from dead vegetation. What is this process called?
Solution : Million years ago, earth was having dense forests in low lying wet land 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. This process of coal formation is called carbonization.

Question 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 vehicle is ________________.
Solution :
(a) Coal, Petroleum and Natural gas.
(b) Refining
(c) CNG

Question 5. Tick true/False against the following statements.
(a) Fossils fuels can be made in laboratory.   (T/F)
(b) CNG is more polluting fuel than petrol.    (T/F)
(c) Coke is almost pure form of carbon.    (T/F)
(d) Coal tar is a mixture of various substances.   (T/F)
(e) Kerosene is not a fossil fuel.     (T/F)
Solution :
(a) F
(b) F
(c) T
(d) T
(e) F

Question 6. Explain why fossil fuels are exhaustible natural resources.
Solution : The process of formation of fossil fuels requires millions of years. Dead vegetation and animals that get buried deep inside the earth require high temperature and pressure for the formation of fossil fuels, which cannot be done in the laboratory. Thus, fossils are limited. Therefore, the use of fossil fuels at this rate will lead to their exhaustion.

Question 7. Describe characteristics and uses of coke.
Solution : Coke is a tough porous black substance. It is 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 formation of petroleum.
Solution : Petroleum is formed from organism living in the sea. When these organism died, their bodies settled at the bottom of the sea and got covered with layers of the sand and clay. Over millions of years, they were transformed into petroleum oil and natural gas under the absence of air and presence of high temperature and high 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.	Year	Shortage (%)
1.	1993	7.7
2.	1994	7.5
3.	1995	8.2
4.	1996	7.1
5.	1997	7.7
6.	1998	9.1
7.	1999	11.2

Solution :