Science Ncert_exemplar 2019 Solutions for Class 8 Science Chapter 5 Coal And Petroleum are provided here with simple step-by-step explanations. These solutions for Coal And Petroleum are extremely popular among Class 8 students for Science Coal And Petroleum Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Science Ncert_exemplar 2019 Book of Class 8 Science Chapter 5 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Science Ncert_exemplar 2019 Solutions. All Science Ncert_exemplar 2019 Solutions for class Class 8 Science are prepared by experts and are 100% accurate.

Page No 24:

Question 1:

Various materials which are obtained from nature are called natural resources. Which of the following is not a natural resource?
(a) minerals
(b) water
(c) soil 
(d) plastic

Answer:

Plastic is a manmade material and therefore, not a natural resource.

Hence, the correct answer is option D. 
 

Page No 24:

Question 2:

Air is a natural resource and cannot be exhausted by human activities. It is known as inexhaustible natural resource. Which of the following is another inexhaustible natural resource?
(a) coal
(b) petroleum
(c) sun-light 
(d) minerals

Answer:

Sunlight is an inexhaustible natural resource.

Hence, the correct answer is option C.

Page No 24:

Question 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) wild life and minerals

Answer:

Exhaustible natural resources are resources which are limited in nature and can be exhausted by human activities. Examples include forests, wildlife, minerals, coal, petroleum, natural gas etc.

Hence, the correct answer is option D.

Page No 24:

Question 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

Answer:

Compressed Natural Gas (CNG) is another fossil fuel and much cleaner fuel than coal. It is not obtained from coal.

Hence, the correct answer is option D.

Page No 24:

Question 5:

Exhaustible natural resources are:
(a) unlimited in quantity.
(b) not dependent on nature.
(c) limited in quantity.
(d) not exhausted by human activities.

Answer:

Exhaustible natural resources are limited in quantity. They can be exhausted by human activities. 

Hence, the correct answer is option C.

Page No 24:

Question 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.

Answer:

Fossil fuels are obtained from dead remains of living organisms (fossils).

Hence, the correct answer is option D.

Page No 24:

Question 7:

Coal is formed from the remains of
(a) vegetation only
(b) animals only
(c) both vegetation and animals 
(d) neither vegetation nor animals

Answer:

Coal is formed from the remains of vegetation only under high pressure and high temperature over millions of years.

Hence, the correct answer is option A.



Page No 25:

Question 8:

Which substance is formed by the carbonisation of dead vegetation?.
(a) coal
(b) coke
(c) coal gas 
(d) coal tar

Answer:

The slow process of conversion of dead vegetation into coal is called carbonisation.

Hence, the correct answer is option A.

Page No 25:

Question 9:

Naphthalene balls are obtained from coal tar and are used as
(a) mosquito repellant
(b) honey bee repellant
(c) moth repellant 
(d) snake repellant 

Answer:

Naphthalene balls are obtained from coal tar and are used as moth repellant.

Hence, the correct answer is option C.

Page No 25:

Question 10:

Which of the following is not a constituent of petroleum?
(a) paraffin wax
(b) lubricating oil
(c) petrol 
(d) coke

Answer:

Petroleum is a mixture of various constituents such as petroleum gas, petrol, diesel, lubricating oil, paraffin wax, etc. Coke is produced from coal.

Hence, the correct answer is option D.

Page No 25:

Question 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

Answer:

Petroleum was formed from organisms living in the sea. Over millions of years, absence of air, high temperature and high pressure transformed the dead organisms into petroleum and natural gas.

Hence, the correct answer is option C.

Page No 25:

Question 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 can not 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. 

Answer:

Natural gas is a naturally occurring hydrocarbon gas mixture of combustible gases. It is formed underground by the decomposition of organic materials in plants and animals. The transport of natural gas is difficult through pipelines because the friction in the pipeline causes the gas to heat up.

Hence, the correct answer is option A.

Page No 25:

Question 13:

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

Answer:

Petroleum is lighter than water and present as a separate layer above water as they do not mix with each other. They can be separated by the process of decantation. 

Page No 25:

Question 14:

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

Answer:

The full form of CNG is Compressed Natural Gas. It is considered to be a better fuel than petrol because it is less polluting and a cleaner fuel.

Page No 25:

Question 15:

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

Answer:

Kerosene is the petroleum product used as fuel for stoves, lamps and jet aircrafts.

Page No 25:

Question 16:

 Fill in the blanks in the following sentences.
(a) Coal is one of the ________ used to cook food.
(b) When heated in air, coal burns and produces mainly ________ gas.
(c) Coal tar is a black, thick ________ with an ________ smell.
(d) Petroleum, ________ and ________ are fossil fuels.
(e) Forests and coal are ________ natural resources.

Answer:

(a) Coal is one of the fuels used to cook food.
(b) When heated in air, coal burns and produces mainly carbon dioxide gas.
(c) Coal tar is a black, thick liquid with an unpleasant smell.
(d) Petroleum, coal and natural gas are fossil fuels.
(e) Forests and coal are exhaustible natural resources.



Page No 26:

Question 17:

The underlined words in the following sentences have been jumbled up. Write them in their correct form.
(a) Loca is obtained from mines.
(b) Umpetlore is a fossil fuel.
(c) Rineryfe is a place where various fractions of petroleum are separated.
(d) Keenrose is a fuel used in jet crafts.
(e) Nutsgilh is an example of inexhaustible natural resources.

Answer:

(a) Coal is obtained from mines.
(b) Petroleum is a fossil fuel.
(c) Refinery is a place where various fractions of petroleum are separated.
(d) Kerosene is a fuel used in jet crafts.
(e) Sunlight is an example of inexhaustible natural resources.

Page No 26:

Question 18:

Fill in the blanks.
(a) The slow process of conversion of dead vegetation into coal is called__________.
(b) Coal and petroleum are formed from the dead remains of organisms and are known as __________.
(c) The black thick liquid with __________ smell is known as coal tar.
(d) During the processing of coal to get coke, coal tar and __________ are also obtained.
(e) The process of separating the various constituents of petroleum is known as __________.
(f) Excessive burning of fossil fuels is a major cause of __________.

Answer:

(a) The slow process of conversion of dead vegetation into coal is called carbonisation.
(b) Coal and petroleum are formed from the dead remains of organisms and are known as fossil fuels.
(c) The black thick liquid with unpleasant smell is known as coal tar.
(d) During the processing of coal to get coke, coal tar and coal gas are also obtained.
(e) The process of separating the various constituents of petroleum is known as refining.
(f) Excessive burning of fossil fuels is a major cause of air pollution.

Page No 26:

Question 19:

Write True/False against the following statements
(a) Oxygen in air is an exhaustible natural resource.
(b) Resources which are present in unlimited quantity in nature are called exhaustible natural resources.
(c) Wildlife is an exhaustible natural resource.
(d) Under high temperature and pressure, dead plants get slowly converted to coal.
(e) CNG is less polluting fuel than petrol and diesel.

Answer:

(a) Oxygen in air is an exhaustible natural resource. False
(b) Resources which are present in unlimited quantity in nature are called exhaustible natural resources. False
(c) Wildlife is an exhaustible natural resource. True
(d) Under high temperature and pressure, dead plants get slowly converted to coal. True
(e) CNG is less polluting fuel than petrol and diesel. True

Page No 26:

Question 20:

Sunlight and air are inexhaustible natural resources. Comment.

Answer:

Sunlight and air are present in unlimited quantity in nature and are not likely to be exhausted by human activities. Therefore, they are known as inexhaustible natural resources.

Page No 26:

Question 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.

Answer:

Exhaustible natural resources: Coal, natural gas, petroleum, minerals, and forests
Inexhaustible natural resources: Air, sunlight, and oxygen



Page No 27:

Question 22:

Write two important uses of coke.

Answer:

Two important uses of coke are:

  • It is used in the manufacture of steel.
  • It is used in the extraction of many metals. 

Page No 27:

Question 23:

Write the characteristics and some important uses of coal.

Answer:

Characteristics of coal:

  • It is as hard as stone and is black in colour.
  • When heated in air, coal burns and produces mainly carbon dioxide gas.
Some important uses of coal:
  • Coal is one of the fuels used to cook food.
  • It is used in thermal power plants to produce electricity.
  • It is used as a fuel in various industries.

Page No 27:

Question 24:

Look at figure where petroleum and natural gas deposits are shown. Why do we find oil layer above water layer?

Answer:

Oil layer is present above water layer because oil is lighter than water and do not mix with it.

Page No 27:

Question 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.

Answer:

About 300 million years ago the earth had dense forests in low lying wetland areas. Due to natural processes, like flooding, these forests got buried under the soil. As more soil deposited over them, they were compressed. The temperature also rose as they sank deeper and deeper. Under high temperature and high pressure, dead plants got slowly converted into coal.

Page No 27:

Question 26:

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

Column I Column II
(a) Used for road surfacing (i) Black gold
(b) Natural gas (ii) Vaseline and candles
(c) Petroleum (iii) Bitumen
(d) Paraffin wax (iv) CNG

Answer:

Column I Column II
(a) Used for road surfacing (iii) Bitumen
(b) Natural gas (iv) CNG
(c) Petroleum (i) Black gold
(d) Paraffin wax (ii) Vaseline and candles



Page No 28:

Question 27:

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

Answer:

Coal is processed in industry to get products such as coke, coal tar and coal gas.

Uses:

  • Coke: It is used in the manufacture of steel and in the extraction of many metals.
  • Coal tar: Products obtained from coal tar are used as starting materials for manufacturing synthetic dyes, explosives, perfumes, plastics, photographic materials, roofing materials, etc.
  • Coal gas: It is used as a fuel in many industries situated near the coal processing plants.

Page No 28:

Question 28:

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

Answer:

Fossil fuels are exhaustible natural resources because their amount is limited in nature. They were formed from the dead remains of living organisms (fossils) over millions of years. Under high temperature and high pressure, dead plants got slowly converted to coal. Also, petroleum and natural gas were formed from organisms living in the sea over millions of years in the absence of air, high pressure and high temperature. They are the main fuels used in transport vehicles and industries. Hence, the fossil fuels are being used across the world widely and will last only for a few hundred years.

Page No 28:

Question 29:

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

Answer:

Burning of fossil fuels leads to production of carbon dioxide and other harmful gases which cause air pollution and greenhouse effect. Nowadays, a lot of such gases are being released into the atmosphere because of large number of vehicles and industries. Petrol is used as a fuel in motor cycles, scooters and cars. Heavy motor vehicles like trucks and tractors run on diesel. It is also used in thermal power plants to produce electricity. Coal gas is used as a fuel in many industries situated near the coal processing plants. This has led to the accumulation of carbon dioxide in the atmosphere. As a result, the average temperature of the earth’s atmosphere is gradually increasing which is called global warming. 

Page No 28:

Question 30:

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

Answer:

The tips that must be followed to save petrol/diesel/natural gas while driving are:

  • Ensure correct tyre pressure.
  • Ensure regular maintenance of the vehicle.
  • Drive at a constant and moderate speed so that wastage of fuels can be conserved
  • Switch off the engine at traffic lights or at a place where you have to wait.
  • Avoid using the air-conditioner whenever possible. 

Page No 28:

Question 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? 

Answer:

Yes, survival of living beings would be possible. In fact, the air quality will become very good.
Humans could then completely switch over to inexhaustible natural resources such as sunlight and air. Instead of fossil fuels, the use of alternative fuels would become a trend for our energy requirements. These could be solar energy, hydropower and wind energy.

Page No 28:

Question 32:

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

Answer:

The amount of petrol in nature is limited. It is obtained from petroleum which was formed from transformation of dead organisms living in the sea over millions of years in absence of air under high temperature and high pressure. And, it is being widely used used to run motor cycles and cars. So, it will be exhausted by human activities in near future. Hence, it is exhaustible natural resource. On the other hand, sunlight is present in unlimited quantity in nature and are not likely to be exhausted by human activities. Therefore it is not an exhaustible natural resource.

Page No 28:

Question 33:

Write some important uses of the various constituents of petroleum.

Answer:

Some important uses of the various constituents of petroleum are as follows:

  • Petroleum Gas in Liquid form (LPG): Fuel for home and industry
  • Petrol: Motor fuel, aviation fuel, solvent for dry cleaning
  • Kerosene: Fuel for stoves, lamps and for jet aircrafts
  • Diesel: Fuel for heavy motor vehicles, electric generators
  • Lubricating oil: Lubrication
  • Paraffin wax: Ointments, candles, vaseline etc.
  • Bitumen: Paints, road surfacing

Page No 28:

Question 34:

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

Answer:

Yes, we need to worry because coal is an exhaustible natural resource. It was formed from the dead vegetation under high pressure and high temperature over millions of years. Therefore, it is also called a fossil fuel. It would take million of years to form coal after the present coal reserves would be depleted. A lot of industries are dependent on coal such as steel manufacturing industries and industries involved in extraction of metals. Thermal power plants use coal to produce electricity. Hence, we need to use coal judiciously so that it is available for a longer period of time. Also, we should switch to cleaner fuels for our energy requirements.

Page No 28:

Question 35:

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

Answer:

The following steps should be adopted for the judicious use of fossil fuels:

  • Carpooling should be encouraged.
  • More use of public transport.
  • Use of bicycles instead of motor cycles and scooters while going for shopping in nearby areas.
  • Engines of motor vehicles should be switched off at red light areas and places where one has to wait.
  • Vehicles should be regularly checked for maintenance.

Page No 28:

Question 36:

 Complete the crossword Fig. 5.2 with the help of the clues:

Across
1. Fuels obtained form 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 form 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)

Answer:



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