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Summary
Pollution happens when our environment’s natural quality changes badly. Chemical, physical, or biological factors cause these changes. Environmental pollution is an unfavorable alteration of our surroundings, mainly from human actions. This affects people, animals, and other organisms. Harmful substances causing pollution are called pollutants. Pollutants are released into nature in large amounts. They disrupt ecosystems and contaminate air, water, or soil.
Pollutants are classified in various ways. Biodegradable pollutants, like sewage, can be broken down by microbes. Non-biodegradable pollutants, like plastic and pesticides, degrade very slowly or not at all. Primary pollutants, such as smoke or carbon dioxide, enter the environment directly from sources. Secondary pollutants, like smog or ozone, form when primary pollutants react in the air, often becoming more toxic. Quantitative pollutants, like carbon dioxide, exist naturally but become harmful in large amounts. Qualitative pollutants, like pesticides, are man-made and not naturally found in the environment.
Different environmental parts suffer from pollution. Air pollution occurs when too much foreign matter, like harmful gases or dust, is in the air. This harms humans, animals, and plants. Water pollution alters water’s characteristics, making it unfit for use. Waste from homes, industries, or farms contaminates rivers, lakes, and oceans. This reduces oxygen, harms aquatic life, and can spread diseases. Marine pollution can create ‘dead zones’. These are ocean areas with too little oxygen for most sea life. Soil pollution happens when harmful substances contaminate the soil. This can be from industrial waste or overuse of fertilizers. It reduces soil fertility and can transfer pollutants into our food through plants.
Radioactive pollution is an increase in natural background radiation due to human activities. These activities involve using radioactive materials for nuclear weapons or power. Nuclear accidents, such as at Chernobyl, release dangerous radiation. This radiation stays harmful for centuries and causes serious health risks.
Noise pollution is unwanted sound that irritates and causes stress. Loud sounds are generally considered noise. Noise pollution directly affects people, even if it doesn’t harm air, soil, or water directly. Constant loud noise can reduce sleep, lower work efficiency, and disturb peace. Common sources include industries, traffic, and loud speakers.
Textbook solutions (Morning Star/Total)
Multiple-Choice Questions
1. Any change in the natural quality of the environment brought about chemical, physical or biological factors:
(a) Pollution
(b) Dust
(c) Humidity
(d) Pollutants
Answer: (a) Pollution
2. The products which are released into the biosphere in large quantities and which affect the normal functioning of ecosystems:
(a) Pollution
(b) Dust
(c) Humidity
(d) Pollutants
Answer: (d) Pollutants
3. Any unfavourable alteration of our surroundings, wholly or largely as a byproduct of man’s actions:
(a) Pollution
(b) Environmental Pollution
(c) Humidity
(d) Pollutants
Answer: (b) Environmental Pollution
4. The alteration in characteristics of water, making it unsuitable for designated use in its natural state:
(a) Air Pollution
(b) Water Pollution
(c) Soil Pollution
(d) Radioactive Pollution
Answer: (b) Water Pollution
5. The pollutants which are formed from the chemical reaction of primary pollutants in the environment:
(a) Biodegradable pollutants
(b) Secondary pollutants
(c) Quantitative pollutants
(d) Non-Biodegradable pollutants
Answer: (b) Secondary pollutants
6. The excessive concentration of foreign matter in the air which adversely affects the well-being of human beings, animals, plants and their environment:
(a) Air Pollution
(b) Pollution
(c) Soil Pollution
(d) Radioactive Pollution
Answer: (a) Air Pollution
7. The pollutants which are not degraded by microbes or degrade at a very slow rate:
(a) Biodegradable pollutants
(b) Primary pollutants
(c) Quantitative pollutants
(d) Non-Biodegradable pollutants
Answer: (d) Non-Biodegradable pollutants
8. Unwanted sound that is an irritant and source of stress:
(a) Air pollution
(b) Radioactive pollution
(c) Noise pollution
(d) Soil pollution
Answer: (c) Noise pollution
9. Which of the following is an example of soil pollution?
(a) Disposal of solid waste in the open
(b) Dumping sewage in the open
(c) Overuse of fertilizers
(d) All of the above.
Answer: (d) All of the above.
10. Nuclear fuels produce pollution by
(a) heat
(b) end products
(c) wastes in coolants
(d) All of the above.
Answer: (d) All of the above.
Short Answer Questions
1. What is environmental pollution? What is a pollutant?
Answer: Environmental pollution refers to any unfavourable alteration of our surroundings, wholly or largely as a byproduct of man’s actions. These changes may affect man and other organisms.
A pollutant is a substance present in the environment in harmful concentration which contaminates air, water or soil. Pollutants are the products which are released into the biosphere in large quantities and which affect the normal functioning of ecosystems and have an adverse effect on plants, animals and man. They affect adversely the environment, human beings and other organisms.
2. Give the difference between natural and man-made pollutants.
Answer: The difference between natural and man-made pollutants lies in their origin. Pollution may be natural, originating from sources like volcanic eruptions, or it can be anthropogenic or man-made, such as from industrial pollution. Man-made pollutants are often introduced into the environment through man’s activities; for example, qualitative pollutants like pesticides (DDT), chemical fertilizers, and herbicides do not naturally exist in the environment. In contrast, natural pollutants originate from natural processes or sources.
3. What is air pollution? Give a source of air pollution.
Answer: Air pollution is defined as the excessive concentration of foreign matter in the air which adversely affects the well-being of human beings, animals, plants and their environment.
A source of air pollution is automobiles, which release primary pollutants such as Nitrogen oxides and hydrocarbons.
4. Define water pollution.
Answer: Water pollution is the alteration in physical, chemical or biological characteristics of water, making it unsuitable for designated use in its natural state. The World Health Organization (WHO) has also defined water pollution as any foreign material either from natural or other sources that may contaminate the water supply and make it harmful to life.
5. What is soil pollution? Why should we avoid soil pollution?
Answer: Soil pollution is defined as the change in physical, chemical and biological conditions of the soil through man’s intervention resulting in degradation in quality and productivity of the soil.
We should avoid soil pollution because it results in the degradation in quality and productivity of the soil. Additionally, the pollutants enter the food chain at the plant level and get magnified as we move up the food chain. Soil pollution also differs from water and air pollutions in the sense that the pollutants remain in the soil for relatively longer periods.
6. What is radioactive pollution?
Answer: Radioactive pollution is defined as the increase in natural background radiation, emerging from the activities of man using naturally occurring or artificially produced radioactive materials.
7. What is noise pollution?
Answer: Noise pollution is defined as an unwanted sound that is an irritant and a source of stress.
Structured Questions
1. (a) With reference to pollution, explain the following:
(i) Air pollution
Answer: Air pollution is defined as the excessive concentration of foreign matter in the air which adversely affects the well-being of human beings, animals, plants and their environment.
(ii) Water pollution.
Answer: Water pollution can be defined as alteration in physical, chemical or biological characteristics of water, making it unsuitable for designated use in its natural state. WHO has defined water pollution as any foreign material either from natural or other sources that may contaminate the water supply and make it harmful to life.
(b) Explain what is radioactive pollution.
Answer: Radioactive pollution is defined as the increase in natural background radiation, emerging from the activities of man using naturally occurring or artificially produced radioactive materials.
(c) What are man-made causes of radioactive pollution? Why is radioactive pollution more harmful than other types of pollution?
Answer: Man-made causes of radioactive pollution originate from the use of radioactive materials. These materials are used in the production of nuclear weapons and nuclear fuel. The radioactive material used in atom bombs is very destructive. Nuclear fuels in atomic reactors produce pollution. During this process, two types of wastes are formed: (i) the fission products remaining in both the primary and secondary fuels, and (ii) waste products in the coolant. The disposal of radioactive wastes causes pollution. Leakage in nuclear reactors causes environmental pollution.
Radioactive pollution is harmful because the radioactive material used in atom bombs is very destructive. We are aware of the impact of radioactivity on man and environment during the Second World War when the US dropped atom bombs on Hiroshima and Nagasaki in Japan in August 1945. The high level products of nuclear wastes remain in the environment for several hundred years. Leakage in nuclear reactors may result in the death of a number of people as happened at Chernobyl Atomic Reactor in the erstwhile USSR on April 26, 1986.
(d) How is noise a source of pollution? Why do we need to look at the problem of noise pollution seriously?
Answer: Noise is a source of pollution as it is an unwanted sound that is an irritant and a source of stress. Noise is a physical form of pollution which is not directly harmful to the life supporting systems namely air, soil and water; its effects are more directly felt by the receiver, i.e., man.
We need to look at the problem of noise pollution seriously, because although noise pollution is not fatal to human life, yet its effects cannot be overlooked because (i) repeated exposure to noise reduces the sleeping hours (ii) productivity or efficiency of a human being (iii) it affects the peace of mind and invades the privacy of a human being.
Thinking Skills
1. Which type/types of pollution is/are more prominent in the city where you live? List the causes and possible remedies.
Answer: In the city where I live, air and noise pollution are the most prominent types of pollution.
Causes of air pollution:
- Emissions from vehicles such as cars, buses, and motorcycles release harmful gases like carbon monoxide, sulphur dioxide, and nitrogen oxides.
- Industrial activities release smoke and chemical fumes into the atmosphere.
- Burning of garbage and use of firecrackers during festivals further degrade air quality.
Remedies:
- Promoting public transport, carpooling, and the use of electric vehicles to reduce emissions.
- Enforcing stricter emission norms for industries and encouraging the use of cleaner technologies.
- Planting more trees to absorb pollutants and improve air quality.
Causes of noise pollution:
- Heavy traffic on roads, honking of horns, and loudspeakers during events.
- Industrial machinery and construction work generate continuous loud sounds.
- Household appliances and entertainment systems contribute to indoor noise pollution.
Remedies:
- Creating silent zones around hospitals, schools, and residential areas.
- Regulating the use of loudspeakers and enforcing limits on noise levels.
- Encouraging people to use noise-reducing technologies and adopt quieter alternatives.
2. Environmental pollution is an incurable disease which can only be prevented. Justify this statement giving examples.
Answer: Environmental pollution causes long-lasting and often irreversible damage to nature and human health. For example, once harmful chemicals enter the soil or water, they remain for years, affecting crops, animals, and people. Pollutants like plastic and radioactive waste do not degrade easily and can harm living beings for decades.
Prevention is the only effective solution. If we avoid using plastic bags and switch to eco-friendly alternatives, we prevent soil and water pollution. If factories treat their waste before releasing it into rivers, water bodies remain clean and safe for marine life and humans. Similarly, using clean energy sources like solar power can prevent air pollution caused by burning fossil fuels.
Thus, just like a disease that cannot be cured once it has spread too far, pollution cannot be undone easily. The best way to protect our environment is to stop pollution before it starts.
Practical Work
Write down five harmful effects of using non-biodegradable products like plastic bags. Suggest measures that can help to replace plastic bags with eco-friendly products.
Answer: Five harmful effects of using non-biodegradable products like plastic bags:
- They remain in the environment for a very long time as they degrade very slowly or not at all.
- They pollute the soil and reduce its fertility, which affects plant growth.
- When thrown into water bodies, they cause water pollution and harm aquatic life.
- Animals may eat plastic bags by mistake, which can cause injury or even death.
- The production and burning of plastic bags release toxic gases, contributing to air pollution.
Measures to replace plastic bags with eco-friendly alternatives:
- Use cloth bags or jute bags when shopping.
- Reuse old bags and avoid buying new plastic ones.
- Spread awareness in schools and communities about using alternatives.
- Support shops and companies that use biodegradable packaging.
- Request authorities to ban single-use plastic in schools and public places.
Extras
Additional MCQs
1. What best defines environmental pollution?
A. Unfavourable environmental alteration
B. Reduction in biodiversity
C. Natural ecosystem process
D. Increase in vegetation
Answer: A. Unfavourable environmental alteration
35. Which of the following is a waste product formed in nuclear reactors?
A. Fission products
B. Agricultural runoff
C. Domestic garbage
D. Industrial smoke
Answer: A. Fission products
Additional Assertion and Reason
1. Assertion (A): The term ‘pollution’ refers to any change in the natural quality of the environment.
Reason (R): This change is brought about by chemical, physical or biological factors.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R does not explain A.
(c) A is true but R is false
(d) A is false but R is true
Answer: (a) Both A and R are true and R is the correct explanation of A.
20. Assertion (A): Eighty per cent of marine pollution comes from the ocean itself.
Reason (R): Mining for materials such as copper and gold is a major source of contamination in the ocean.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R does not explain A.
(c) A is true but R is false
(d) A is false but R is true
Answer: (d) A is false but R is true
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