Important Questions Class 8 Science Chapter 5

Important Questions Class 8 Science Chapter 5 – Coal and Petroleum

Chapter 5 of Class 8 Science is about ‘Coal and Petroleum’. We use different materials for our basic needs. Some are found in nature, and human efforts have made some of these materials. The number of resources in nature is limited; they can be exhausted by human activities. These include coal, petroleum and natural gas and other fossil fuels. Coal and petroleum are important natural resources and play a vital role in modern society. They are found in the earth’s crust.

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Important Questions Class 8 Science Chapter 5 comprises questions and solutions to various topics from the chapter Coal and Petroleum. These topics cover coal, petroleum, natural gas and other fossil fuels, types of fossil fuels, the formation of fossil fuels, limitations of using fossil fuels and uses of fossil fuels. Our solved question bank of the Important Questions Class 8 Science Chapter 5 will make it easy for students to revise the entire chapter before the exams. These solutions will help theoretically and logically comprehend the Chapter 5 Class 8 Science questions.

Students must understand all topics with clarity and practice as many questions from the chapter before the  exams. For this purpose, our experienced Science faculty has prepared comprehensive study materials such as NCERT solutions, CBSE revision notes, CBSE sample papers, etc. To avail the maximum benefit, students can register on our website and get full access to all our study resources including Science Class 8 Chapter 5 Important Questions.

Get Access to CBSE Class 8 Science Important Questions 2022-23 with Chapter-Wise Solutions

You can also find CBSE Class 8 Science Chapter-by-Chapter Important Questions here:

CBSE Class 8 Science Important Questions
Sr No. Chapters Chapters Name
1 Chapter 1 Crop Production and Management
2 Chapter 2 Microorganisms : Friend and Foe
3 Chapter 3 Synthetic Fibres and Plastics
4 Chapter 4 Materials : Metals and NonMetals
5 Chapter 5 Coal and Petroleum
6 Chapter 6 Combustion and Flame
7 Chapter 7 Conservation of Plants and Animals
8 Chapter 8 Cell Structure and Functions
9 Chapter 9 Reproduction in Animals
10 Chapter 10 Reaching The Age of Adolescence
11 Chapter 11 Force and Pressure
12 Chapter 12 Friction
13 Chapter 13 Sound
14 Chapter 14 Chemical Effects of Electric Current
15 Chapter 15 Some Natural Phenomena
16 Chapter 16 Light
17 Chapter 17 Stars and The Solar System
18 Chapter 18 Pollution of Air and Water

Important Questions Class 8 Science Chapter 5 – With Solutions

Extramarks team has collated a comprehensive list of Important Questions Class 8 Science Chapter 5 based on the latest CBSE curriculum and  question papers and NCERT books.. This will help the students to understand the exam question pattern and prepare with confidence.. 

Chapter 5 Class 8 Science Important Questions provides question-answer solutions including MCQs, short answer questions, long answer questions, etc. The step-wise solutions have been prepared based on the latest CBSE syllabus and guidelines while adhering to  the NCERT books. So students can confidently rely on our solutions for Important Questions Class 8 Science Chapter 5. 

Following are some of the questions and their answers from our question set of Class 8 Science Chapter 5 Important Questions.

Question 1. Which one of the following is not fossil fuel?

  1. Coal
  2. Oil
  3. Natural Gas
  4. Biogas

Answer 1:: The correct option is D – Biogas

Fossil fuels are mostly derived from decomposing plants and animals. Coal, natural gas and oil are examples of natural gas. Biogas is a mixture of gases that break organic matter without oxygen, usually consisting of certain quantities of methane and other constituents. Therefore, biogas is not a fossil fuel.

Question 2. What is petroleum? How is it formed?

Answer 2: Petroleum is an exhaustible type of natural resource. Petrol and diesel are obtained from petroleum. Petroleum is obtained deep inside water in the sea or oceans. 

Petroleum is formed from various dead organisms which are found inside water. The bodies of these dead organisms settle at the bottom of the ocean, get covered with soil, sand, or various other aquatic plants, and start decaying slowly. Over a millions of years, these dead organisms turn into petroleum or natural gas because of the non-availability of proper and sufficient oxygen, heat, and constant pressure. 

Question 3. Describe the characteristics and uses of coke.

Answer 3: Coke is a black and solid substance produced from coal and used as a fuel.

The characteristics of coke:

  • It is the purest form of carbon.
  • Coke is black, tough and porous as a substance.
  • When coke is burnt, there is no production of smoke.
  • To obtain coke, the coal is burnt in the absence of air.

Uses of coke:

  • It is used widely as fuel.
  • It is used for the extraction of different metals.
  • It is also used in the manufacturing of steel.

Question 4. Describe how the coal is formed from dead vegetation. What is the process called?

Answer 4: The decomposition of large land trees and plants buried under the earth’s surface about 300 million years ago led to the coal formation. Around 300 million years ago, our earth had a dense forest, especially in low-lying wet areas. At that time, there were many frequent natural calamities occurring. So, the dense forest was buried under the earth’s surface due to natural calamities like floods, earthquakes, volcanoes, etc. As there was more and more soil deposition on the surface of the earth, the pressure started increasing; this compressed the underlying vegetation.

As we know, the temperature increases when we go deeper into the earth’s surface. As the vegetation began to sink deeper and deeper, the temperature consequently started to rise. So, at high pressure and temperature and without air, small plants and animals and wood started slowly converting into coal. This process is known as carbonization.

So, carbonization can be defined as a slow process in which the dead trees and plants under the earth’s surface in high pressure and temperature form coal. It is called fossil fuels because of the dead remains of plants from it. So, when coal is heated, carbon dioxide and heat energy are formed.

Question 5. Air is a natural resource and cannot be exhausted by several human activities. It is also known as an inexhaustible natural resource. Which of the following is an inexhaustible natural resource? 

(a) coal 

(b) minerals

(c) sunlight 

(d) petroleum

Answer 5: The correct option is C- Sunlight.

Sunlight is another inexhaustible natural resource as it is continuously available and cannot be exhausted by human activities..

Whereas petroleum, minerals, and coal are exhaustible natural resources of energy that can be exhausted in  future with human activities and are available in limited quantity.

Question 6. We read in newspapers that burning fuels is a major cause of global warming. Explain why.

Answer 6: Fossil fuels are generally mixtures of carbon-based compounds. The burning of several fossil fuels such as petroleum, natural gas and coal produces carbon dioxide gas, a greenhouse gas. The increase and rise in levels of carbon dioxide in the atmosphere causes global warming. There are many different causes of global warming, which have a negative effect on humans, plants and animals. These causes may be natural or might be the outcome of human activities.

Question 7. Why do we need to use coal and petroleum judiciously?

Answer 7: – Coal and petroleum have been produced using large amounts of biomass trapped in the earth under great temperature, pressure, and anaerobic conditions. Such situations develop only rarely, like a big upheaval on earth.

– At present, there is no more coal or petroleum being formed. All that is available was formed millions of years ago. Being a rich energy source, coal and petroleum are being consumed in ever-increasing enormous amounts in the industry, transport, kitchens, etc.

– If this trend continues, soon they will be exhausted. Therefore, they must be conserved and protected by developing more efficient machines and hybrid engines and using hydrogen as a fuel. It is correct that both these natural resources, coal and petroleum, are produced by the biodegradation of plants and animal wastes, but it takes thousands of years to form.

– This is why we need to conserve them for future generations, as we are using them much faster than the rate at which these natural resources  are formed.

– We should use them judiciously because-

They are an important source of fuel. Petroleum products like petrol, diesel, etc., are used as fuel in automobiles.

Coal is used in various thermal power plants to generate electricity and as fuel for domestic purposes.

Question 8. We say that fossil fuels will last only for a few hundred years. Comment​ 

Answer 8: Fossil fuels will last only a few hundred years because they are exhaustible natural resources. It takes millions of years to convert dead and decaying materials into fossil fuels in nature..​

Question 9. 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 9: The answer (c) living in the sea

Petroleum was obtained from organisms living in the sea. As these organisms were killed or died, their bodies settled down at the bottom of the sea bed and got covered with layers of sand and clay. Over millions of years, the absence of air, high pressure and high temperature transformed the dead organisms into petroleum and natural gas.

Question 10. Explain why fossil fuels are called exhaustible natural resources.

Answer 10. Fossil fuels are generated from the dead remains of living organisms. Forming fossil fuels is very slow; it takes millions of years. Hence, the resources available for use are limited and are being exhausted by human activities like industrialization, rapid growth, etc. Thus, fossil fuels are an exhaustible natural resource.

  • Fossil fuels are capable of generating a huge amount of electricity at a single place.
  • They can be found very easily.
  • They are cost-effective and inexpensive.
  • Transportation of oil and gas can be easily done through pipelines.
  • They have become a safe option over time.
  • Despite being a finite resource, fossil fuels are available in plenty.

Question 11. Explain the use of coal and its products.

Answer 11. Uses of coal:

i) Coal is one of most widely y used fuel  to cook food.

ii) Earlier, it was in use for railway engines for production of steam to run the engine.

iii) It is used in thermal power plants for electricity production.

iv) Coal is used as a fuel in various industries and power plants.

v) Coke is used in the manufacture of steel and the extraction of  metals.

vi) Coal gas is used as a fuel in many industries near coal processing plants.

vii) Products obtained from coal tar are used as starting materials for manufacturing various substances used in everyday life and industry, like synthetic dyes, drugs, explosives, perfumes, plastics, paints, photographic materials, roofing materials, etc.

Question 12. What is refining? Why does petroleum require refining?

Answer 12:  The process of separating the different constituents of petroleum at various boiling points is known as refining. Natural petroleum is a crude dark liquid with a very unpleasant and foul smell. Petroleum cannot be used in its crude form. Hence, we discover petroleum in several different products, such as diesel, petrol, and wax and use it for various purposes.

Question 13. How is petroleum useful to us? What are examples of petroleum products?

Answer 13: Mostly petroleum is utilised as a source of energy, rich in fuel carbon in electricity generation or running some heat engines. Raw petroleum which is also known as crude oil is used in three main ways: transport, generating electricity, and producing materials. Examples of different petroleum products include kerosene, home heating oil,gasoline and diesel fuel. Petroleum products are complex mixtures that are derived from crude oil and other sources and have similar chemical and physical properties.

Benefits of Solving Important Questions Class 8 Science Chapter 5

The solutions for all questions in our Important Questions Class 8 Science Chapter 5 are explained in easy  steps. The students can  understand the explanations provided for each question  and clear all doubts regarding the chapter. 

By practising MCQs, short answers, medium answers, and long answer questions provided with stepwise solutions, students will get well versed with question pattern and the  key concepts in the chapter. Furthermore, the other  benefits of referring to Important Questions Class 8 Science Chapter 5 are given below:

  • The questions-answers given have been curated by the Extramarks subject experts Subject experts have created several pointwise notes that help students conveniently recall the crucial points in the exam and use these solutions for last-minute revisions.  .
  • The step-wise solutions help students to revise and understand the important theory concepts included in the chapter and get good grades.
  • Students can entirely rely on the Extramarks solutions as they are based and have been compiled carefully per the NCERT books while adhering to the  latest CBSE syllabus and guidelines. 
  • The questions provided are generally expected  in the examinations. This helps students to create a general idea of the type of questions that are expected to appear in the exams and prepare thoroughly with confidence.

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Q.1 Which organisation in India, is associated with the conservation of petrol and diesel?

Ans

Petroleum Conservation Research Association (PCRA) is associated with the conservation of petrol and diesel.

Q.2 What are natural resources?

Ans

Resources obtained from the nature are called natural resources. E.g., coal, petroleum, etc.

Q.3 What are the various constituents of petroleum? Give their uses.

Ans

Constituents of petroleum are petroleum gas, petrol, kerosene, diesel, lubricating oil, paraffin wax and bitumen.

S.No.

Constituents of petroleum

Uses

 

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

Q.4 Why petroleum is known as black gold?

Ans

Petoleum is a black oily liquid. Its fractional distillation yields a range of combustible fuels, petrochemicals and lubricants. These petrochemicals are used in the manufacture of detergents, synthetic fibres (polyester, nylon, acrylic etc.), polythene and other man-made plastics. Also, hydrogen gas obtained from natural gas, is used in the production of fertilisers such as urea.

Hence, petroleum is called ‘black gold’ due to its great commercial importance and appearance.

Q.5 Write short note on natural gas.

Ans

Natural gas is a very important fossil fuel consisting primarily of methane. It is stored under high pressure as compressed natural gas (CNG). CNG is used for power generation and also as a fuel for transport vehicles because it is less polluting. Natural gas is also used as a starting material for the manufacture of a number of chemicals and fertilisers.

It is a cleaner fuel. The greatest advantage of CNG is that it can be used directly for burning in homes and factories where it can be supplied through pipes.

Q.6 Coal is a fossil fuel. Explain.

Ans

Due to natural processes, like flooding, dead plants got buried under the soil. As more soil deposit over them, they were compressed. The temperature also rose as they sank deeper and deeper. Under high pressure and high temperature, dead plants got slowly converted to coal. As coal contains mainly carbon, the slow process of conversion of dead vegetation into coal is called carbonisation. As it was formed from the remains of vegetation, coal is also called a fossil fuel.

Q.7 What are the advantages of using CNG and LPG as fuels?

Ans

Advantages of using CNG and LPG as fuels are as follows:

1. They are less polluting and are cleaner fuels.

2. Their cost is low.

3. The great advantage of CNG is that it can be used directly for burning in homes and factories where it can be supplied through pipes.

Q.8 Give one use of each of the following:

(i) Coke

(ii) Coal tar

(iii) Coal gas

Ans

(i) Coke is used in the manufacture of steel and in the extraction of many metals.
(ii) Coal tar is used for metalling the roads.
(iii) Coal gas is used as a fuel in many industries situated near the coal processing plants.

Q.9 Write three uses of coal.

Ans

Uses of coal are as follows:

1. In thermal power plants to produce electricity

2. In the manufacture of coke, coal tar and other useful products

3. As domestic fuels for cooking purposes

Q.10 Give a brief account on

(i) Exhaustible natural resources

(ii) Inexhaustible natural resources

Ans

Exhaustible natural resources: The amount of these resources in nature is limited. They can be exhausted by human activities. Examples of these resources are forests, wildlife, minerals, coal, petroleum, natural gas etc.

Inexhaustible natural resources: These resources are present in unlimited quantity in nature and are not likely to be exhausted by human activities. E.g., sunlight, air etc.

Q.11 Write the constituents of petroleum.

Ans

The constituents of petroleum are petroleum gas, petrol, kerosene, diesel, lubricating oil, paraffin wax and bitumen.

Q.12 How is carbon black prepared?

Ans

Carbon black is prepared by burning oils and the petroleum gas in insufficient supply of air.

Q.13 Write the products obtained by processing of coal.

Ans

Coke, coal gas and coal tar are the three products obtained by processing of coal.

Q.14 Give two examples of exhaustible and inexhaustible natural resources.

Ans

Coal and petroleum are examples of exhaustible natural resources.

Sunlight and air are examples of inexhaustible natural resources.

Q.15 What are the constituents of natural gas?

Ans

Natural gas contains 95% methane and 5% of other hydrocarbons.

Q.16 What is the full form of PCRA?

Ans

PCRA is Petroleum Conservation Research Association.

Q.17 What are inexhaustible natural resources?

Ans

Inexhaustible natural resources are the resources which are present in unlimited quantity in nature and are not likely to be exhausted by human activities.For example, sunlight, air, etc.

Q.18 What are exhaustible natural resources?

Ans

Exhaustible natural resources are the resources whose amount in the nature is limited. They can be exhausted by human activities. Examples: coal, petroleum and natural gas.

Q.19 What are the fossil fuels?

Ans

The fuels which are obtained from the dead remains of living organisms are known as fossil fuels.

Q.20 How dead plants are converted into coal?

Ans

Under high pressure and high temperature, dead plants got slowly converted into coal. This process is known as carbonisation.

Q.21 Explain the term carbonisation.

Ans

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

Q.22 What is bitumen?

Ans

Bitumen is a petroleum product. These days, bitumen is used in place of coal tar for metalling the roads.

Q.23 How can we obtain the coal gas?

Ans

Coal gas is obtained as a by-product during the processing of coal to get coke.

Q.24 Explain the formation of petroleum.

Ans

Petroleum was formed from organisms living in the sea. The remains of these organisms got settled at the bottom of the sea and subsequently got covered with sand and clay. Over millions of years, absence of air, high temperature and high pressure, transformed these dead organisms into petroleum.

Q.25 Define the term coal tar.

Ans

Coal tar is a black, thick liquid with unpleasant smell. It is a mixture of about 200 substances.

Q.26 Explain the term petroleum refining.

Ans

The process of separating the various constituents/ fractions of petroleum is known as refining. It is carried out in a petroleum refinery.

Q.27 Why should we use the fossil fuels economically and wisely?

Ans

The deposits of fossil fuels are limited. It requires millions of years for the dead organisms to get converted into these fuels. On the other hand, the known reserves of these will last atmost a few hundred years.
Moreover, burning of these fuels is a major cause of air pollution. Their use is also linked to global warming.
So, we should use the fossil fuels economically and wisely.

Q.28 Give tips to save petrol/diesel while driving.

Ans

Tips to save petrol/diesel while driving are as follows:

(i) Drive at a constant and moderate speed as far as possible.

(ii) Switch off the engine at traffic lights or at a place where we have to wait.

(iii) Ensure correct tyre pressure.

(iv) Ensure regular maintenance of the vehicle.

Q.29 Can the fossil fuels be prepared in the laboratory? If not, Why?

Ans

Fossil fuels cannot be prepared in the laboratory because their formation is very slow process. It requires very high temperature and pressure and takes millions of years. The conditions for the formation of fossil fuels cannot be created in the laboratory.

Q.30 Draw a neat and clean diagram of petroleum refinery.

Ans

Diagram is as follows:

Q.31 How petroleum is mined from their deposits?

Ans

Petroleum is brought to the surface by drilling a hole in the Earth’s crust and sinking pipes deep down through the impervious cap rock. Natural gas first comes out under high pressure. Then, petroleum is pumped out, collected in tanks and transported for further processing.

Q.32 (i) What is carbonisation?
(ii) Name three products obtained after the processing of coal. Also mention their uses.

Ans

(i)The slow process of conversion of wood into coal is called carbonisation.

(ii)The three products obtained by processing of coal are:

1) Coke: It is a pure form of carbon, which is tough, porous and black in colour. It is used in the manufacture of steel and extraction of many metals.

2) Coal gas: It is used for street lighting.

3) Coal tar: It is a black thick liquid with unpleasant smell. Coal tar is a mixture of several substances.

It is used for manufacturing dyes, drugs, perfumes, naphthalene balls etc.

Q.33 Define refining of petroleum. Where it is carried out?

Ans

The process of separating the various fractions by fractional distillation is known as refining of petroleum. It is carried out in a petroleum refinery.

Q.34 Write four uses of petrochemicals.

Ans

1) Petrochemicals are used in the manufacture of detergents.
2) They are used in the manufacture of fibres (polyester, nylon and acrylic).
3) They are used in the manufacture of polythene.
4) They are used in the manufacture of man-made plastics.

Q.35 Write two advantages of using CNG as a fuel.

Ans

1) It can be supplied by pipes and used directly at home and factories.
2) It is used as a fuel for transport vehicles because it is less polluting.

Q.36 (i) What are petrochemicals?(ii) Why petroleum is called black gold?

Ans

(i)The useful substances that are obtained from petroleum and natural gas are called petrochemicals.

(ii) Due to its great commercial importance, petroleum is called black gold.

Q.37 Name the places in India where reserves of natural gas are found.

Ans

Natural gas is found in Tripura, Rajasthan, Maharashtra and Krishna Godavari delta.

Q.38 Where do we find reserves of petroleum and natural gas – above water or below water? Why?

Ans

Petroleum and natural gas reserves are found above water because petroleum and natural gas are lighter than water.

Q.39 Write two advantages of using CNG as a fuel.

Ans

Following are the advantages of using CNG as a fuel:

1) It can be supplied by pipes and used directly at home and factories.
2) It is used as a fuel for transport vehicles because it is less polluting.

Q.40 Write four uses of petrochemicals.

Ans

Uses of petrochemicals are as follows:

1) They are used in the manufacture of detergents.
2) They are used for making synthetic fibres (polyester, nylon and acrylic).
3) They are used in the manufacture of polythene.
4) They are used in making plastics.

Q.41 Define refining of petroleum. Where is it carried out?

Ans

The process of separating the useful fractions from petroleum by fractional distillation is known as refining. It is carried out in a petroleum refinery.

Q.42 What is carbonisation? Name three products obtained after the processing of coal. Also mention their uses.

Ans

The slow process of conversion of wood into coal is called carbonisation.

The three products obtained by processing of coal are:

1) Coke: It is a pure form of carbon, which is tough, porous and black in colour. It is used in the manufacture of steel and extraction of many metals.

2) Coal gas: It is used for street lighting.

3) Coal tar: It is a black thick liquid with unpleasant smell. It is a mixture of several substances. It is used for manufacturing dyes, drugs, perfumes, naphthalene balls etc.

Q.43 (i)What are petrochemicals?

(ii) Why petroleum is called black gold?

Ans

(i)The useful substances that are obtained from petroleum and natural gas are called petrochemicals.

(ii) Due to great commercial importance of petroleum, it is called black gold.

Q.44 Name the places in India where reserves of natural gas are found.

Ans

Natural gas is found in Tripura, Rajasthan, Maharashtra and Krishna Godavari delta.

Q.45 Where do we find reserves of petroleum and natural gas – above water or below water? Why?

Ans

Petroleum and natural gas reserves are found above water because petroleum and natural gas are lighter than water.

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FAQs (Frequently Asked Questions)

1. What topics and subtopics are covered in Chapter 5 of Class 8 Science?

The topics and various sub topics covered in Chapter 5 of Class 8 Science are 

  1. Story of Coal
  2. Coal gas
  3. Coal tar
  4. Coke
  5. Fossil fuel
  6. Natural gas
  7. Petroleum
  8. Refining of Petroleum
  9. Some Natural Resources Are Limited

2. What type of questions are asked from Class 8 Coal and Petroleum Chapter 5?

Generally, there are 3-4 types of questions asked in exams from the chapter. These are multiple choice questions or fill-in-the-blanks, short-answer questions, and long-answer questions. A few long answer questions are mentioned in the NCERT exercise questions for reference. Our Science faculty experts from Extramarks have curated a list of question-answers that include all these questions and stepwise solutions. One can access Important Questions Class 8 Science Chapter 5 by registering on Extramarks website.

3. What are the advantages of usage of CNG and LPG as fuels?

The advantages of CNG and LPG usage as fuels are as follows

  • CNG and LPG burn very easily.
  • CNG and LPG give out a lot of heat energy when burnt.
  • CNG and LPG can be easily transported through pipelines.
  • CNG and LPG are clean fuels which do not release smoke when burnt.