Get notes, summary, questions and answers, MCQs, extras, and PDFs of Chapter 19 “Conventional Sources of Energy” which is part of NBSE Class 11 Environment Education. However, the notes should only be treated as references and changes should be made according to the needs of the students.
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Summary
The chapter discusses conventional sources of energy, which are exhaustible and non-renewable. These include coal, petroleum, natural gas, and firewood, which have formed over millions of years from the remains of plants and animals. Once used, they cannot be replaced. Firewood has been a primary source of energy throughout history, especially in rural areas, but it causes air pollution when burned.
Coal, formed from ancient forests, was once the dominant energy source. It is still used today for various purposes, such as producing coke, coal gas, and synthetic petroleum. However, burning coal releases harmful gases like carbon monoxide and sulphur dioxide, leading to air pollution, health problems, and environmental issues like acid rain. Coal mining also causes water pollution, habitat loss, and land degradation.
Petroleum, formed from marine plants and animals, has largely replaced coal as the main energy source. It is refined through fractional distillation into various products like petrol, diesel, and kerosene. Petroleum use, however, leads to air pollution and environmental damage. Oil spills are especially harmful to marine life, and burning petroleum releases pollutants that harm the atmosphere.
Natural gas, often found with petroleum, is another fossil fuel. Its compressed form, CNG, is used in vehicles and is considered a cleaner alternative to petrol and diesel.
The chapter also covers the environmental impacts of using these fuels. Deforestation for firewood leads to soil erosion and habitat loss. Burning fossil fuels contributes to air pollution, global warming, and climate change. Acid rain, caused by sulphur dioxide emissions, harms ecosystems and human health. Despite their widespread use, these sources of energy have significant environmental consequences.
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Textbook solutions
Multiple-Choice Questions
1. Conventional sources of energy are also known as
A. Exhaustible sources of energy
B. Inexhaustible sources of energy
C. Renewable sources of energy
D. All of these
Answer: A. Exhaustible sources of energy
2. Which of the following is used for manufacturing of coke?
A. Petroleum
B. Carbon dioxide
C. Coal
D. Natural gas
Answer: C. Coal
3. Which of the following is not a consequence of coal mining?
A. Water pollution
B. Earthquake
C. Land degradation
D. Loss of animal habitats
Answer: B. Earthquake
4. Incomplete burning of coal produces the following gas
A. Ozone
B. Carbon dioxide
C. Carbon monoxide
D. Oxygen
Answer: C. Carbon monoxide
5. Which product is added to LPG (Liquefied petroleum gas), so as to detect leakage (if any)?
A. Compressed Natural Gas (CNG)
B. Petroleum Gas
C. Mercaptan
D. Butane
Answer: C. Mercaptan
Short Answer Questions
1. What are the conventional sources of energy?
Answer: The sources of energy which are exhaustible are called conventional sources of energy or non-renewable sources of energy. E.g. coal, natural gas, petroleum. These sources have been formed through a series of processes that lasted over millions of years. Once these fuels are used, they will not be available again.
2. What is refining of petroleum?
Answer: The process of separating crude petroleum into more useful fractions is called refining of petroleum.
3. What is fractional distillation?
Answer: Fractional distillation is the process used to separate crude petroleum into various useful fractions. It is done by heating crude petroleum to a temperature of 400°C or above in a furnace, and the vapours are fed into a tall fractionating column. As the vapours rise up the column, they condense at different levels according to their boiling points.
4. What is the main constituent of methane?
Answer: Methane mainly contains the hydrocarbon methane (CH₄), which burns easily to produce heat.
5. What is CNG?
Answer: The compressed form of natural gas is called Compressed Natural Gas (CNG). It is used in automobiles as a fuel.
6. What are the harmful effects of deforestation?
Answer:
- Deforestation leads to soil erosion.
- It causes destruction of habitats of animals and plants.
- Deforestation leads to floods and droughts.
- It also results in increased carbon dioxide levels in the atmosphere.
7. What do you mean by acid rain?
Answer: Acid rain is formed when sulphur dioxide (SO₂) and oxides of nitrogen released into the air react with water vapour to form sulphuric acid and nitric acid. These acids dissolve in rain and snow, leading to acid rain.
8. What are the effects of global warming on the atmosphere?
Answer: Global warming causes the lower atmosphere to become warmer. This leads to more water evaporating into the atmosphere, which further warms the Earth’s atmosphere. This increased warmth causes changes in climate and weather patterns.
9. What is the average temperature rise of the atmosphere in the last 200 years?
Answer: The average temperature of the atmosphere has risen by almost 1°C in the last 200 years.
Long Answer Questions
1. How were coal and petroleum formed?
Answer: Coal is believed to have been formed by the slow compression of forests that existed on Earth 300 million years ago. The intense heat and high pressure under the Earth converted plants into coal. This is why coal is called a fossil fuel.
Petroleum is formed from the dead remains of marine plants and animals which settled in the sea millions of years ago. Intense heat as well as pressure underneath and the presence of natural catalysts converted the remains into petroleum. This is the reason why petroleum is called a fossil fuel.
2. Explain the fractional distillation of petroleum.
Answer: The process of separating crude petroleum into more useful fractions is called refining of petroleum.
The refining of petroleum is done by the process of fractional distillation.
Crude petroleum is heated to a temperature of 400°C or above in a furnace. The vapours of petroleum are fed into a tall fractionating column near its bottom. As the vapours rise up the fractionating column, they lose heat and hence their temperature drops. Due to this difference in temperatures, these vapours with higher boiling points condense first. Similarly, the vapours with lower boiling points rise up and condense in different parts of the fractionating column.
3. Name and define the main types of coal.
Answer:
- Peat: Peat is the first stage of coal formation and contains a large amount of moisture and decaying plant material.
- Lignite: It is a brownish-black coal with high moisture content, used primarily for electricity generation.
- Bituminous: It is a medium grade of coal used for generating electricity and making coke for the steel industry.
- Anthracite: This is the highest grade of coal, hard and black, with the highest carbon content and few impurities. It is used for domestic heating and as a high-quality fuel.
4. What are the harmful effects of fossil fuels?
Answer:
- Air pollution: Fossil fuels like coal and petroleum release pollutants such as sulphur dioxide, nitrogen oxides, carbon dioxide, and carbon monoxide into the air, leading to respiratory problems and environmental issues like acid rain and global warming.
- Water pollution: Oil spills during the transportation of petroleum or its products pollute water bodies and kill marine life.
- Land degradation: Mining of coal leads to the degradation of land, destruction of animal habitats, and loss of vegetation.
- Health hazards: Fossil fuel mining and burning cause serious health issues like pneumoconiosis in miners and respiratory problems in people living near mining areas.
- Global warming: The excessive release of carbon dioxide due to burning fossil fuels leads to global warming and climate change.
5. What is thermal pollution?
Answer: Thermal pollution refers to the impairment of the quality of environmental air or water by raising its temperature. Thermal power stations contribute to thermal pollution in a big way.
Effects:
- The life process involves many chemical reactions, and the rate of these reactions varies with temperature changes. Apart from biochemical reactions, temperature is of great importance to physiology and control of reproductive cycles, digestion, and respiration rates of aquatic animals, particularly fish.
- Most species of fish can adapt themselves to a fairly wide range of water temperature, provided the temperature changes occur very slowly. A steep change in temperature is quite destructive. The temperature change not only affects the fish but also brings about changes in the aquatic ecosystem. Any disruption in the food chain will upset the whole system.
- When the temperature of the aquatic system rises, the metabolic processes taking place in the body of the fish become faster, and its need for oxygen and rate of respiration rise. At a specific temperature, death occurs due to the failure of essential cell processes.
6. Discuss the limitations of the petroleum fuel.
Answer:
- Since it is a non-renewable source of energy, it will last for a few decades.
- Leakage of LPG can form an explosive mixture into the air on catching fire.
- It catches fire easily because it is highly inflammable, so great precautions have to be taken while dealing with petroleum fuels.
- Burning of petrol in vehicles releases poisonous gases into the atmosphere.
- Incomplete combustion of petrol releases poisonous gases like carbon monoxide and carbon particles.
7. Explain the environmental consequences of: (a) Coal, (b) Petroleum.
Answer: (a) Coal:
- Coal mining activities cause water pollution up to a large distance surrounding it.
- Loss of animal habitats, vegetation, and land degradation are the primary results of coal mining.
- A lot of CO (carbon monoxide) gas is released when coal burns in insufficient oxygen, causing damage to human health.
- Combustion of coal releases CO₂ (carbon dioxide) gas, which causes the greenhouse effect in the atmosphere.
- Another toxic pollutant from the coal-burning process is sulphur dioxide, which is injurious to human beings and causes acid rain.
(b) Petroleum:
- During the combustion of petrol in cars or other vehicles, nitrogen dioxide, a poisonous gas, is produced, which is very harmful to humans and other animals.
- Sometimes during the transportation of petroleum (oil), it spills into water bodies or on land. Such accidents cause a great loss of living organisms in that area.
- The lead compounds emitted by vehicles are poisonous and pollute the air.
- The fossil fuels burnt in thermal power stations cause thermal pollution, which increases air and water temperature.
Think and Answer
1. Rohan thinks that global warming is a superstition of the scientists. It has no effect on human beings. How will you convince him that global warming is a grave threat?
Answer: I will tell Rohan that global warming is a scientifically proven phenomenon. It is not a superstition. The Earth’s atmosphere is becoming warmer due to increased carbon dioxide levels caused by human activities, such as burning fossil fuels. This rise in temperature leads to melting polar ice caps, rising sea levels, extreme weather events, and changes in agricultural patterns. These changes affect human beings directly through floods, droughts, and food shortages, proving that global warming is a grave threat.
2. Ridhima thinks that as India has vast reserves of coal, so it does not have to worry about the future. Do you think she is right? Why or why not?
Answer: Ridhima is not completely right. Although India has vast reserves of coal, it is a non-renewable resource. Once these reserves are exhausted, they cannot be replenished. Moreover, coal mining and burning cause significant environmental problems such as air pollution, land degradation, and global warming. Additionally, the increasing global shift towards renewable energy sources means that relying on coal may not be sustainable in the long run. Therefore, India needs to focus on alternative energy sources for the future.
Extras MCQs
1. What are conventional sources of energy also known as?
A. Renewable sources
B. Sustainable sources
C. Non-renewable sources
D. Unlimited sources
Answer: C. Non-renewable sources
25. Which method of energy harnessing has no emissions in the environment?
A. Solar power
B. Geothermal power
C. Natural gas
D. Coal
Answer: B. Geothermal power
Extra Questions and Answers
1. What are conventional sources of energy or non-renewable sources of energy?
Answer: The sources of energy that are exhaustible are called conventional sources of energy or non-renewable sources of energy. These sources include coal, natural gas, and petroleum, which have been formed through processes lasting over millions of years. Once these fuels are used, they will not be available again.
17. What is the greenhouse effect, and how has it contributed to global warming?
Answer: The greenhouse effect is the warming of the Earth’s surface due to the trapping of the sun’s heat by the atmosphere, which acts like the glass in a greenhouse. Modern lifestyles have disrupted the natural balance of atmospheric gases, with exhaust gases from vehicles and power stations adding about 6 billion tonnes of carbon dioxide to the atmosphere. This extra CO₂ has caused the lower atmosphere to become warmer, contributing to global warming, with the average temperature of the atmosphere rising by almost 1°C in the last 200 years.
Ron’e Dutta is a journalist, teacher, aspiring novelist, and blogger who manages Online Free Notes. An avid reader of Victorian literature, his favourite book is Wuthering Heights by Emily Brontë. He dreams of travelling the world. You can connect with him on social media. He does personal writing on ronism.
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