Coal and Petroleum Class 8th Question Answers

Coal and Petroleum is Chapter 2 taken from the JKBOSE textbook of Science for students of Class 8th. In the previous post, I provided you with Questions and Answers for Chapter 1 Microorganisms Friends and Foe. This post is about Coal and Petroleum Class 8th Question Answers. Before we move on to solutions you must have your basics clear. So, let me begin by giving you a brief overview of what you have studied in this chapter.

Coal and Petroleum Class 8th Question Answers

Overview of Chapter

• COAL (STORY OF COAL).
• HOW COAL IS FORMED?
• COKE, COAL TAR, COAL GAS.
• PETROLEUM (FORMATION & REFINING).
• NATURAL GAS.
• SOME NATURAL RESOURCES ARE LIMITED.

We use a variety of materials in our daily routine to fulfil our needs. Like we need pen and paper to write, clothes to wear, air to breathe, water to drink, bus to travel. We term all these materials as a resource. A resource is a source or supply that we can utilize to fulfil our needs. There are various types of resources like natural resources and man-made resources. Natural resources are further grouped as inexhaustible and exhaustible resources.

1. a) Inexhaustible Natural Resources: – Those natural resources which are present in unlimited quantity in nature and are not likely to get vanished by human activities in future. E.g. sunlight, air, soil and water etc.
2. b) Exhaustible Natural Resources: – Those natural resources which are present in limited quantity in nature and can be exhausted in future by uncontrolled human activities. E.g. Forests, wildlife, coal, petroleum, minerals and natural gas etc.

COAL (STORY OF COAL): Coal is a hard, black, stone-like combustible material which mainly consists of carbon. It is found in deep coal mines under the surface of the earth. It is an important source of energy in our country. In India coal is mainly found in Bihar, West Bengal, Orrisa and Madhya Pradesh.

HOW COAL IS FORMED? Coal is formed from the decomposition of large plants and trees which buried under the earth about 300 million years ago. Our earth had dense forests in low-lying wetland areas. These forests got buried under the surface of the earth due to natural causes like flooding, volcanoes, etc.

As time passed more and more soil got deposited over them, and they got compressed. The temperature inside the earth rose as they sank deeper and deeper. Due to high temperatures, high pressure and the absence of air inside the earth, the wood of dead plants slowly got converted into coal. As plants mainly have carbon dioxide in them, the slow process of conversion of dead plants under the earth into coal is called carbonization.

COKE, COAL TAR, COAL GAS: When coal is heated strongly in the absence of air in close retorts, it produces various useful products. The various useful products obtained by processing coal in absence of air are:

1. Coke: It is a tough, porous and black solid substance. It is an almost pure form of carbon. It has about 98 % carbon.
2. Coal tar: It is a thick black liquid having an unpleasant smell. It is obtained by heating coal in the absence of air. It is a mixture of about 200 substances
3. Coal gas: It is a gaseous fuel obtained during the processing of coal to obtain coke. It is mainly a mixture of methane and hydrogen with some carbon monoxide.

PETROLEUM (FORMATION & REFINING): Petroleum is a thick, dark-coloured crude oil with an unpleasant smell. It is found deep below the crust of the earth trapped in rocks at certain places. It is a complex mixture of compounds known as hydrocarbons. It is also known as crude oil or mineral oil.

Formation of Petroleum: Petroleum was formed from the remains of tiny plants and animals buried under the sea millions of years ago. The plants and animals which lived in the sea died and their dead bodies settled at the bottom of the sea got buried under mud and sand. Due to high temperatures and pressure inside the earth and in the absence of air, these dead remain slowly got converted into petroleum and natural gas.

Extraction and Refining of Petroleum: Petroleum is extracted by drilling holes termed oil wells in the earth’s crust. These oil wells are drilled by using drilling rigs. The world’s first oil well was drilled in Pennsylvania in 1859. Petroleum is pumped out of the oil well. Crude petroleum is a mixture of several substances and is not useful to us as such, so it is refined to separate its various components. It is done by the process of fractional distillation. The various fractions/components of petroleum are Petroleum gas, petrol, diesel, kerosene, lubricating oil, paraffin wax, bitumen etc.

NATURAL GAS: It is a mixture of hydrocarbons mainly methane. The other hydrocarbons which are present in small quantities are ethane and propane. It is found deep inside the earth’s crust either alone or above the petroleum in the oil wells. It is found in Tripura, Rajasthan, Maharashtra and Krishna Godavari delta in India. Natural gas is used as fuel in homes and factories. It is also used as fuel for vehicles such as CNG (Compressed Natural Gas). It is used as a starting material for a number of chemicals called petrochemicals.

SOME NATURAL RESOURCES ARE LIMITED: Natural resources like coal, petroleum and natural gas are fossil fuels and they are present in limited amounts on our earth. The resources like fossil fuels, forests and minerals etc. are exhaustible natural resources. If we consume them at a faster rate than the rate at which they are formed, they will get exhausted from nature very soon. Also, coal and petroleum are fossil fuels. It required the dead organisms millions of years to get converted into these fuels. The burning of fossil fuels also causes air pollution and is responsible for global warming.   It is, therefore, necessary that we use these fuels only when absolutely necessary.  Because:

1. It will result in a better environment.
2. It will decrease the risk of global warming.
3. I will ensure their availability for a longer period of time.

Chapter 2 Coal and Petroleum Class 8 Questions

Exercises

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

Ans. The advantages of using CNG and LPG as fuels are as under: –

a) Both are easy to transport through pipelines or cylinders.

b) They are cheap and have high calorific value.

c) They are clean fuels and cause less pollution.

2. Name the petroleum product used for surfacing roads.

Ans. Bitumen.

3. How is coal formed from dead vegetation? What is the process called?

Ans. Coal is formed from fossils of dead plants and trees. Millions of years ago the earth had dense forests. These forests got buried under the earth due to certain natural causes like flooding, earthquakes and volcanic eruptions etc.

As years passed by more and more layers of soil got deposited over them and they got compressed inside the earth. Due to high temperatures and pressure inside the earth, these fossils of plants slowly got converted into coal. The process of conversion of dead vegetation (fossils) into coal is called carbonization because coal mainly contains carbon.

4. Fill in the blanks

1. Fossil fuels are coal, petroleum and natural gas.
2. The process of separation of different constituents from petroleum is called refining.
3. The least polluting fuel for a vehicle is CNG.

5. Tick True/False against the following statements.

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

(b) CNG is more polluting than LPG. (False)

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

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

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

6. Explain why fossil fuels are called exhaustible natural resources.

Ans. Fossil fuels like coal, petroleum and natural gas are limited in nature and will last for a few hundred years if used judiciously. The process of formation of these fossil fuels is extremely slow and it takes millions of years. If these fuels are used in an unchecked manner they will be used up in near future. That is why these fuels are called exhaustible natural resources.

7. Describe the characteristics and uses of coke.

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

8. Explain the process of formation of petroleum.

Ans. Petroleum is formed from the fossils (dead remains) of animals living in the sea. As living organisms died, they got settled at the bottom of the sea. With the passage of time they got covered by sand and clay and more and more layers of clay and sand got deposited over them. Due to high pressure and temperature inside the earth for millions of years these dead remains of animals got converted into petroleum.

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

Sno.	Year	Shortage (%)
1	1991	7.9
2	1992	7.8
3	1993	8.3
4	1994	7.4
5	1995	7.1
6	1996	9.2
7	1997	11.2

Ans.

10. What are exhaustible natural resources? Give examples.

Ans. Those natural resources are present in limited quantity in nature and can be exhausted in future by uncontrolled human activities.

E.g. Forests, wildlife, coal, petroleum, minerals and natural gas etc.

11. What are inexhaustible natural resources? Give examples.

Ans. Those natural resources are present in unlimited quantity in nature and are not likely to get vanished from human activities in future. E.g. sunlight, air, soil and water etc.

12. Why natural gas is called a clean fuel?

Ans. Natural gas is called clean fuel because it burns completely and does not emit smoke while burning and also causes less pollution.

13. What are the uses of coal?

Ans. Coal is hard, black rock-like substance (fossil fuel). It has the following uses: –

1. It is used as fuel to cook food in homes.
2. It is also used as fuel in steam engines on railways.
3. It is also used in thermal power plants to generate electricity.
4. It is used as fuel in many industrial units.
5. Coal also forms starting material for many products.

That’s all about Coal and Petroleum Class 8th Question Answers. Hope it has helped. Do share your views about this post in the comment section below.