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.

Extramarks is one of the most trusted online educational platforms in India.  The in-house subject experts provide students with the accurate solutions for  all  Classes from 1 to  12..They conscientiously and diligently  prepare authentic, concise answers which students can trust and enjoy the process of learning. They help them to learn at  their own pace and improve their academic performance through guided practice. Our experts believe that students must practice questions and study regularly to score better in exams. For this purpose, they have prepared a question bank of Important Questions Class 8 Science Chapter 5 to guide students. The questions are followed by their detailed answers, which will help students to clarify their doubts for better understanding of  the concepts used in each of the given solutions.

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:

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.

Extramarks believes in incorporating joyful learning experiences through its own repository.To speed up their learning and improve their academic performance,  they must practice the Important Questions Class 8 Science Chapter 5, students should first register on the Extramarks website now, to begin their preparation without any further delay.

Furthermore, students can also gain access to the various study materials by clicking on the below links:

• NCERT books
• CBSE Revision Notes
• CBSE syllabus
• CBSE sample papers
• CBSE’s previous year’s question papers
• Important formulas 
• CBSE extra questions