NCERT Exemplar Class 8 Science Solutions Chapter 5 Coal and Petroleum

Multiple Choice Questions

1. Various materials which are obtained from nature are called natural resources. Which of the following is not a natural resource?

(a) minerals                                   (c) soil

(b) water                                        (d) plastic

Ans: (d) Plastic is a man-made material, not a natural resource. 

2. Air is a natural resource and cannot be exhausted by human activities. It is known as an inexhaustible natural resource. Which of the following is another inexhaustible natural resource?

(a) coal                                             

(b) petroleum  

(c) sun-light                                

(d) minerals

Ans: (c) The sun is an infinite natural resource.

3. Which of the following is a pair of exhaustible natural resources.

(a) coal and soil                       

(b) air and sun-light 

(c) water and petroleum 

(d) wildlife and minerals              

Ans: (c) Water and petroleum are both exhaustible since they are both present in extremely limited quantities and are rapidly depleting due to human use.

4. Coal is processed in industries to get some useful products. Which of the following is not obtained from coal?

(a) coke                                  

(b) coal tar 

(c) coal gas  

(d) CNG                          

Ans: (d) Natural gases are gases that exist beneath the earth's surface as a result of years of decay of plant matter. CNG (compressed natural gas) is not available.

5. Exhaustible natural resources are:

(a) unlimited in quantity.

(b) not dependent on nature.

(c) limited in quantity.

(d) not exhausted by human activities.

Ans: (c) Natural resources that are exhaustible are those whose value diminishes with each usage due to their scarcity.

6. Fossil fuels are obtained from:

(a) remains of non-living materials.

(b) dead remains of birds only.

(c) dead remains of insects only.

(d) dead remains of living organisms.

Ans: (d) Fossils fuels are the fuels that are found in their natural state under the earth's surface. These are the results of years of decay of living beings' dead remains. Petroleum, Coal are examples of fossil fuels.

7. Coal is formed from the remains of

(a) vegetation only

(b) animals only                        

(c) both vegetation and animals                       

(d) neither vegetation nor animals

Ans: (a) Coal is created through the disintegration of plants, trees, and soils over a lengthy period of time. It takes around 300 years for coal to develop.

8. Which substance is formed by the carbonisation of dead vegetation?

(a) coal                                                  

(b) coke

(c) coal gas                                                

(d) coal tar

Ans: (a) Coal is created.

9. Naphthalene balls are obtained from coal tar and are used as

(a) mosquito repellant                              

(b) honey bee repellent 

(c) moth repellent                           

(d) snake repellant

Ans: (c) As a moth repellent, naphthalene balls are utilized.

10. Which of the following is not a constituent of petroleum?

(a) paraffin wax                                         

(b) lubricating oil  

(c) petrol                                     

(d) coke

Ans: (d) Coke. It is synthesized by heating the coal at high temperature in the absence of air.

11. Petroleum was formed from organisms:

(a) living on the land                            

(b) living on the plants

(c) living in the sea                         

(d) living on the rocks

Ans: (c) Many million years ago, the decay of plants and animals dwelling in the ocean resulted in the formation of petroleum.

12. Choose the correct statement from the following:

(a) It is difficult to transport natural gas through pipes.

(b) The disadvantage of natural gas is that it cannot be used directly for burning in homes.

(c) Natural gas is stored under high pressure as compressed natural gas.

(d) Natural gas cannot be used for power generation.

Ans: (c) Natural gas is utilized to generate power. It is simple to transport natural gas through pipelines. In many places, it is burned and cooked directly in houses.

Very Short Answer Questions

13. You are provided with a mixture of petroleum and water. Can you suggest a method to separate the two?

Ans: Petroleum has a lower density than water. The procedure of decantation can be used to separate these two. Because light petroleum floats on top of the water, it can be carefully poured. So, This strategy makes it simple to separate them.

14. What does CNG stand for and why is it considered to be a better fuel than petrol?

Ans: CNG (Compressed Natural Gas) is a better fuel than gasoline since it is less destructive to the environment and less expensive. It doesn't produce any smoke and doesn't pollute the environment.

15. Name the petroleum product used as fuel for stoves, lamps and jet aircrafts.

Ans: Kerosene is a petroleum-based substance. It's used to power lamps, stoves, and jet planes.

16. Fill in the blanks in the following sentences.

(a) Coal is one of the ________ used to cook food.

Ans: Coal is one of the fuels used to cook food

(b) When heated in air, coal burns and produces mainly________gas.

Ans: When heated in air, coal burns and produces mainly carbon dioxide gas. 

(c) Coal tar is a black, thick ________ with an ________smell.

Ans: Coal tar is a black, thick Liquid with an unpleasant smell.

(d) Petroleum, ________ and ________ are fossil fuels.

Ans: Petroleum, coal and natural gas are fossil fuels.

(e) Forests and coal are ________ natural resources.

Ans: Forests and coal are exhaustible natural resources 

17. The underlined words in the following sentences have been jumbled up. Write them in their correct form.

(a) Loca is obtained from mines

Ans: Coal

(b) Umpetlore is a fossil fuel

Ans: Petroleum

(c) Rineryfe is a place where various fractions of petroleum are separated.

Ans: Refinery

(d) Keenrose is a fuel used in jet crafts.

Ans: Kerosene

(e) Nutsgilh is an example of inexhaustible natural resources.

Ans: Sunlight

18. Fill in the blanks.

(a) The slow process of conversion of dead vegetation into coal is called__________.

Ans: carbonisation

(b) Coal and petroleum are formed from the dead remains of organisms and are known as __________.

Ans: fossil fuel

(c) The black thick liquid with __________ smell is known as coal tar.

Ans: unpleasant

(d) During the processing of coal to get coke, coal tar and __________ are also obtained.

Ans: coal gas

(e) The process of separating the various constituents of petroleum is known as __________.

Ans: air pollution

(f) Excessive burning of fossil fuels is a major cause of __________.

Ans: global warming

19. Write True/False against the following statements.

(a) Oxygen in air is an exhaustible natural resource

Ans: False, Oxygen is a nonrenewable natural resource that can be reused many times.

(b) Resources which are present in unlimited quantity in nature are called exhaustible

natural resources.

Ans:  False, Natural resources that are inexhaustible are those whose quantity is not dependent on consumption or is not subject to scarcity.

(c) Wildlife is an exhaustible natural resource.

Ans: True

(d) Under high temperature and pressure, dead plants get slowly converted to coal.

Ans: True

(e) CNG is less polluting fuel than petrol and diesel.

Ans: True

Short Answer Questions

20. Sunlight and air are inexhaustible natural resources. Comment.

Ans: Natural resources that are inexhaustible are those whose quantity is not dependent on consumption or is not subject to scarcity. The amount of sunshine available and the air we breathe is not reliant on human usage. As a result, these natural resources are limitless.

21. Some natural resources are given in a box. Classify them into the exhaustible and

inexhaustible natural resources. Air, coal, natural gas, sunlight, petroleum, minerals,

forests, oxygen.

Ans: Exhaustible Natural Resources- Natural gas, Coal, Petroleum, Forests, Minerals.

Inexhaustible Natural Resources- Air, Oxygen, Sunlight

22. Write two important uses of coke.

Ans: Some basic important uses of coke are given below-

(i) Used as a reducing agent in extraction of metals.

Example- Zinc and Iron, etc.

(ii) It is used in steel manufacturing.

23. Write the characteristics and some important uses of coal.

Ans: Following are the important characteristics of coal-

(i) It's a fossil fuel.

(ii) It's a flammable and hard fuel.

(iii) It contains a significant amount of carbon.

(iv) It is an energy source.

Important uses:

(i) It is used to generate power and as a source of heat in dwellings to prepare food.

(ii) It's used to generate coal gas and coke.

24. Look at Fig. 5.1 where petroleum and natural gas deposits are shown. Why do we find oil layers above water layers?

Ans: Oil is lightweight and thus floats over it.

25. Fill in the blanks and complete the story.

About 300 million years ago the earth had dense ________ in low lying wetland areas.

Due to natural processes, like ______, these forests got buried under the ________. As

more ________ deposited over them, they were compressed. The ________ also rose

as they sank deeper and deeper. Under high ________ and high ________, dead plants

got slowly converted into coal.

Ans: forests, floods, soil, soil, temperature, pressure, temperature.

26. Match the items given in Column I with the items of Column II.

Ans: Followings are the correct matching for the given items-

(a)-(iii)

(b)-(iv)

(c)-(i)

(d)-(ii)

Long Answer Questions

27. Name the products obtained and their uses when coal is processed in industry.

Ans: Following products can be obtained by processing coal in the industry-

(i) Coal tar- used in making roads.

(ii) Coke- used as a domestic fuel to cook food.

(iii) Coal Gas- Methane, hydrogen, and carbon monoxide are all present in this gas. These gases allow it to burn. Therefore, used in the routine preparation of cuisine homes.

28. We say fossil fuels will last only for a few hundred years. Comment.

Ans: The transformation of the dead creature into petroleum, coal, and natural gas takes millions of years. They have a finite amount of resources. Fossil fuels are utilized in a variety of ways. However, generation and reserves are merely a few of the sources from which these are derived. People are relying on these fuels to get by in their daily lives. Fossil fuels contribute to the generation of electricity, which is then wasted. It contributes to the production of gasoline and diesel for automobiles. People are unconcerned about squandering it. Despite the fact that these fuels are more expensive, consumers do not pay attention to them. The intensive consumption of fossil fuels makes it difficult to believe that they will last for much longer.

29. We read in newspapers that burning of fuels is a major cause of global warming. Explain why.

Ans: The biggest concern produced by the use of fossil fuels in various places is air pollution. Sulphur dioxide, carbon dioxide, and other hazardous gases are produced when fossil fuels are burned. By heating the atmosphere and air, these gases raise the earth's temperature. The gases emitted by automobiles, power plants, factories, and homes, among other things, contribute to an increase in the temperature of the environment and the earth. The global temperature is rising as a result of this. Worldwide warming refers to an increase in the earth's temperature on a global scale, which is why we frequently see this editorial in newspapers.

30. While driving what are the tips we must follow to save petrol/diesel/natural gas?

Ans: We can follow the following tips to save the petrol, diesel, and natural gas-

(i) We should maintain a consistent speed in our automobiles. Vehicles that travel at excessive speeds waste a lot of gasoline.

(ii) We should turn off our automobiles when there are indications. It aids in the reduction of fuel use.

(iii) Low-pressure and high-pressure tyre vehicles a significant amount of fuel is wasted

31. Imagine that all the exhaustible natural resources are exhausted by human
activities. Do you think survival of living beings would be possible? If yes, why? If not, why not?

Ans: Human survival would be impossible if all natural resources were to be depleted. Fossil fuels are necessary for human survival. If there is one item that is absolutely vital for human survival after oxygen and food, it is fossil fuel. Fossil fuels are used to generate energy, which is used to power industries and manufacture all of the other necessities of existence. Humans may not be able to exist for long without these necessities. Apart from them, humans use fossil fuels to power their automobiles. Human life will come to a halt without fuel. It'll become sluggish and ineffective. Fossil fuels are responsible for the majority of human productivity. As a result, fossil fuels are critical to human survival.

32. Why is petrol an exhaustible natural resource, whereas sunlight is not? Explain.

Ans: Petrol is a fossil fuel created by the breakdown of dead plants and animals in the waters over millions of years. It can only be found in a few locations. This fossil fuel is used to make petrol. It's a dwindling resource. The more restricted it is, the more ferociously humans use it. That is why gasoline is a finite resource. Sunlight, on the other hand, is a source of energy created by the sun through nuclear fission. A lot of energy is produced in this process. And it will carry on indefinitely, at least as long as the inhabitants of Earth are alive.

33. Write some important uses of the various constituents of petroleum.

Ans: Below are the uses of important constituents of petroleum-

(i) LPG gas is used to cook food in houses.

(ii) Automobiles run on petrol.

(iii) Diesel is used in big vehicles 

(iv) Vehicle engines make use of lubricating oils.

34. Coal reserves are said to be enough to last for another hundred years. Do you think we need to worry in such cases? Why or why not?

Ans: Coal deposits are quite scarce. A coal deposit is only good for about 100 years. With the rate at which humans consume coal, it's doubtful that it'll survive another 100 years. The consumption of coal is steadily increasing. Coal is widely used, from modest homes to large enterprises and power plants. As a result, coal is becoming scarce. Nature takes millions of years to create this fossil fuel within the earth. However, the consumption is so great that it will not last long. As a result, we must use coal with caution and responsibility. Aside from that, we should utilize other renewable energy sources.

35. What steps would you suggest for the judicious use of fossil fuels?

Ans: Below are some judicious uses of fossil fuels-

(i) Only utilize fossil fuels when they are absolutely necessary and there are no other options.

(ii) Make use of natural gas. It has less contaminants. In the last two decades, the natural gas resources have expanded tenfold.

(iii) Other energy sources should be considered as well.

(iv) Renewable energy sources are the greatest to use because they can be recycled.

36. Complete the crossword with the help of the clues: 

Across

1. Fuels obtained from dead remains of living organisms. (6,5)

2. A process by which the various constituents of petroleum

are separated. (8)

3. A porous black substance obtained from coal. (4)

4. Another name for motor fuel. (6)

Down

5. The substance obtained by carbonisation. (4)

6. Fuel for heavy motor vehicles. (6)

7. A petroleum product used for road surfacing. (7)

8. Dead remains of sea animals got converted into it. (9)

Ans:

Across 

1- Fossil fuels 

2- Refining

3- Coke 

4- Petrol

Down

5- Coal 

6- Diesel

7- Bitumen

8- Petroleum