Glossary with Definitions:
Term | Definition |
Pollution | The addition of harmful substances into the environment causing adverse effects. |
Air Pollutants | Unwanted substances that contaminate the air and cause harm. |
Carbon Monoxide | A poisonous gas formed by incomplete combustion of carbon-containing fuels. |
Nitrogen Dioxide | A reddish-brown toxic gas contributing to smog and acid rain. |
Smog | A thick fog-like layer made of smoke and pollutants in the atmosphere. |
Acid Rain | Rainwater that becomes acidic due to the presence of sulphuric and nitric acids. |
Greenhouse Effect | The trapping of the Sun’s heat by greenhouse gases, warming the Earth’s atmosphere. |
Global Warming | A gradual increase in the Earth’s average temperature due to greenhouse effect. |
Marble Cancer | The corrosion and damage of marble structures due to acid rain. |
Chlorofluorocarbons (CFCs) | Harmful gases that deplete the ozone layer when released into the atmosphere. |
Deforestation | Large-scale cutting down of trees leading to environmental imbalance. |
Vanmahotsava | A tree-planting festival celebrated to promote afforestation. |
Ozone Layer | A protective layer in the atmosphere that absorbs harmful ultraviolet radiation from the Sun. |
Carboxyhaemoglobin | A complex formed between carbon monoxide and haemoglobin, blocking oxygen transport in blood. |
Something To Know
A. Fill in the blanks.
- __________ and __________ gases dissolve in water to form acid rain.
Answer – Sulphur dioxide, nitrogen dioxide
- The phenomena of corrosion of marbles of the monument, by acid rain, is called__________
Answer – Marble cancer
- __________ and __________ are two of the main greenhouse gases.
Answer – Carbon dioxide, methane
- The phenomenon, of likely increase in earth’s average temperature (due to increase in the amount of greenhouse gases), is known as __________ .
Answer – Global warming
B. State True or False for the following statements.
- Burning of fossil fuels is one of the many causes of air pollution.
Answer – True
- High concentration of nitrogen dioxide, in the atmosphere, can result in respiratory problems.
Answer – True
- The ultraviolet rays of the sun get absorbed mainly by the oxygen present in the atmosphere.
Answer – False (The ultraviolet rays are mainly absorbed by the ozone layer.)
- Acid rain does not corrode metals.
Answer – False (Acid rain can corrode metals and other materials.)
- Sulphur dioxide is one of the ‘greenhouse gases’.
Answer – False (Sulphur dioxide is not a greenhouse gas; it is a pollutant that causes acid rain, but it does not trap heat like greenhouse gases.)
C. Tick (✓) the correct option.
- Which of the following is responsible for depletion of ozone layer?
smog
carbon monoxide
nitrogen dioxide
chlorofluorocarbon
Answer – chlorofluorocarbon
- An increase, in the amount of carbon dioxide and methane in the atmosphere, is likely to lead to—
ozone depletion
global warming
acid rain
formation of more glaciers
Answer – global warming
- The main gases, that trap the solar heat radiations after their reflection from the earth, are—
methane, carbon monoxide, chlorofluorocarbon
carbon dioxide, methane, water vapours
carbon monoxide, nitrogen dioxide and chlorofluorocarbons, water vapours
carbon monoxide, methane, nitrogen dioxide, water vapours
Answer – carbon dioxide, methane, water vapours
- Taj Mahal, at Agra, may get damaged if its surrounding atmosphere contains more of—
sulphur dioxide
nitrogen
oxygen
hydrogen
Answer – sulphur dioxide
- Smoke combines with water vapours and dust particles, in the presence of sunlight, to form—
snow
smog
fog
dew
Answer – smog
D. Answer the following questions in brief:
- Define the term ‘pollutant’.
Answer – A pollutant is any substance that is present in the environment in quantities greater than its natural abundance, causing harmful effects to the environment and living organisms.
- State two causes of air pollution.
Answer – Burning of fossil fuels like coal, petrol, and diesel.
Emissions from industries and motor vehicles.
- How is carboxy haemoglobin formed?
Answer – Carboxy haemoglobin is formed when carbon monoxide, produced by incomplete combustion of fuels, combines with haemoglobin in the blood. This complex reduces the blood’s ability to carry oxygen, causing suffocation.
- State the harmful effects of chlorofluorocarbons.
Answer – Chlorofluorocarbons (CFCs) cause the depletion of the ozone layer. This leads to increased ultraviolet radiation from the sun, which can cause skin cancer, cataracts, and damage to aquatic life.
- Suggest any three measures that can help to check global warming.
Answer – Minimize the use of fossil fuels (e.g., wood, coal, petrol).
Reduce deforestation and increase afforestation (plant more trees).
Use alternative sources of energy such as solar, wind, and hydroelectric power.
E. Answer the following questions.
- Give the meaning of the term ‘smog’. List its harmful effects.
Answer – Smog is a thick fog-like layer of air pollution, typically formed when smoke and fog combine, especially in the presence of sunlight.
Harmful effects of smog:
It causes respiratory problems like asthma, bronchitis, and other lung diseases.
It reduces visibility, making driving dangerous.
It prevents sunlight from reaching the Earth, affecting plant photosynthesis.
- Write a short note on ‘acid rain’.
Answer – Acid rain is a type of rain that has a lower pH than normal rain, making it acidic. This occurs when pollutants like sulphur dioxide and nitrogen oxides, released by burning fossil fuels, react with water vapour in the atmosphere, forming sulfuric acid and nitric acid.
Harmful effects:
It corrodes buildings and monuments, especially those made of marble and limestone (e.g., Taj Mahal).
It depletes essential minerals from soil, harming crops.
It affects aquatic life in lakes and rivers.
- List the main causes of increase in concentration of greenhouse gases in the atmosphere.
Answer – Burning of fossil fuels (coal, petrol, diesel) in power plants, industries, and vehicles.
Deforestation, reducing the number of trees that absorb carbon dioxide.
Agricultural activities, including livestock farming and the use of chemical fertilizers.
Industrial processes and the use of CFCs (chlorofluorocarbons) in refrigerants and air conditioners.
- State the likely consequences of an increase in the ‘greenhouse effect’.
Answer – Global warming: The Earth’s average temperature rises, leading to melting glaciers and rising sea levels.
Extreme weather conditions: More frequent and intense storms, heatwaves, and droughts.
Loss of biodiversity: Changes in climate may make it difficult for many species to survive.
Ocean acidification: Increased carbon dioxide levels lead to more acidic oceans, which harms marine life.
- Write any five methods that can help to control air pollution.
Answer – Use smokeless fuels like biogas, solar cookers, and electric stoves instead of coal and wood.
Use unleaded petrol and cleaner fuels such as CNG in vehicles.
Reduce industrial emissions by installing tall chimneys with filters.
Plant more trees to absorb carbon dioxide and release oxygen (afforestation).
Promote renewable energy sources such as solar, wind, and hydroelectric power to reduce dependence on fossil fuels.
Value Based Question
Ram was walking to his home after school. He noticed that the traffic policeman, on duty at a congested crossing, was not wearing a mask. He immediately went near him and advised the traffic policeman to wear the mask preferably throughout his duty hours but definitely during the peak hours of traffic. The policeman thanked him for his suggestion.
- Do you agree with Ram’s suggestion that the policeman should wear a mask during his duty hours?
Answer – Yes, I agree with Ram’s suggestion. Wearing a mask, especially during peak traffic hours at a congested crossing, can help protect the policeman from inhaling harmful pollutants in the air, such as carbon monoxide and nitrogen dioxide, which are released by vehicles. These pollutants can negatively affect respiratory health, and wearing a mask can help reduce exposure.
- Name the main pollutant produced by combustion of petrol/gasoline in automobiles.
Answer – The main pollutant produced by the combustion of petrol/gasoline in automobiles is carbon monoxide (CO). It is a harmful gas formed due to incomplete combustion and is dangerous to human health.
- State the values exhibited by Ram.
Answer – The values exhibited by Ram include:
Responsibility: Ram shows a sense of responsibility by noticing the potential health risk and advising the policeman to protect himself.
Concern for health and well-being: He cares about the health of the policeman and the surrounding people by suggesting preventive measures against pollution.
Civic Sense: Ram demonstrates civic responsibility by thinking of ways to improve public health in his community.
Respect for authority: Ram approaches the policeman with respect and offers a constructive suggestion, maintaining politeness and appreciation.
Something To Do
- Visit your nearby petrol pump and observe the process of conducting ’pollution check’ for the petrol and diesel cars. Make a project report, on the basis of your observations, highlighting following points:
(a) average number of vehicles checked per month.
Answer – The average number of vehicles checked for pollution control in a month varies depending on the location and traffic density. In metropolitan areas, around 500-1000 vehicles might be checked per month, while in smaller towns, it could range from 100-300 vehicles. The petrol pump staff records the vehicle details and checks the emissions levels.
(b) pollutants checked for.
Answer – The pollutants typically checked for include:
Carbon monoxide (CO)
Carbon dioxide (CO₂)
Hydrocarbons (HC)
Nitrogen oxides (NOₓ)
Particulate matter (PM) These pollutants are tested using an electronic device or sensor that measures the vehicle’s exhaust emissions to ensure they are within permissible limits.
(c) permissible level of emission of different polluting gases.
Answer – The permissible emission levels of various gases depend on the country and the specific standards in place. In India, for example, under the Bharat Stage (BS) norms, the permissible limits for some gases are as follows:
Carbon monoxide (CO): 0.5% for petrol vehicles and 0.25% for diesel vehicles.
Hydrocarbons (HC): 200 ppm for petrol vehicles and 400 ppm for diesel vehicles.
Nitrogen oxides (NOₓ): 0.25 g/km for petrol vehicles and 0.5 g/km for diesel vehicles.
Particulate matter (PM): 0.025 g/km for diesel vehicles.
These limits are regularly updated as per international standards and newer emission norms like BS-VI.
(d) the pollutants from vehicles, that act as major source of air pollution.
Answer – The permissible emission levels of various gases depend on the country and the specific standards in place. In India, for example, under the Bharat Stage (BS) norms, the permissible limits for some gases are as follows:
Carbon monoxide (CO): 0.5% for petrol vehicles and 0.25% for diesel vehicles.
Hydrocarbons (HC): 200 ppm for petrol vehicles and 400 ppm for diesel vehicles.
Nitrogen oxides (NOₓ): 0.25 g/km for petrol vehicles and 0.5 g/km for diesel vehicles.
Particulate matter (PM): 0.025 g/km for diesel vehicles.
These limits are regularly updated as per international standards and newer emission norms like BS-VI.
- Organise a trip to an industrial area. Talk to the people residing near that area regarding the practical problems they face due to the smoke and emissions by the factories.
Answer – During the trip to an industrial area, residents shared the following practical problems they face due to smoke and emissions from factories:
Air Quality Degradation: Many residents complained of poor air quality due to continuous emissions of smoke and chemicals, causing breathing problems, especially among children and elderly people.
Health Issues: Several residents reported issues like asthma, bronchitis, and other respiratory problems. The emissions from factories worsen these conditions.
Dust Pollution: Residents mentioned that dust and particulate matter from the factories clog windows and make it difficult to maintain cleanliness inside homes.
Foul Smell: The emission of harmful gases like sulfur dioxide and volatile organic compounds led to foul smells in the area, creating discomfort.
Corrosion of Buildings and Monuments: The acidity in the air from factory emissions caused the deterioration of the paint on buildings and monuments.
Noise Pollution: Noise from factory machines and vehicles, as well as heavy machinery used in the factories, led to high noise pollution levels, affecting the mental well-being of the residents.
- Global warming is a matter of worldwide concern. Countries have joined together to find solutions to this problem. Collect information about any two international measures that aim at addressing the issue of ‘global warming’.
Answer – Two major international measures that address global warming are:
(a) Paris Agreement (2015)
The Paris Agreement is a legally binding international treaty on climate change that aims to limit global warming to below 2°C above pre-industrial levels, with efforts to limit the increase to 1.5°C. Countries that signed the agreement (195 countries) committed to reducing greenhouse gas emissions through nationally determined contributions (NDCs), enhancing climate resilience, and providing financial assistance to developing countries.
(b) Kyoto Protocol (1997)
The Kyoto Protocol is an international treaty that commits industrialized countries and economies in transition to limit and reduce greenhouse gas emissions, based on the premise that (a) human-made greenhouse gas emissions are causing global warming and (b) industrialized countries are principally responsible for the current high levels of greenhouse gases in the atmosphere. Countries agreed to take action to reduce emissions during a commitment period. Though it has been succeeded by the Paris Agreement, it set the groundwork for international cooperation on climate change.
Additional Questions And Answers – 01
- What are air pollutants?
Answer – Substances that contaminate the air and cause harm to living and non-living things are called air pollutants.
- What causes smog?
Answer – Smog is caused when smoke containing oxides of nitrogen combines with fog and other pollutants during winters.
- What are the harmful effects of carbon monoxide on the human body?
Answer – Carbon monoxide forms carboxyhaemoglobin with blood, reducing oxygen transport and causing suffocation and even death.
- Define acid rain.
Answer – Rain that becomes acidic due to the presence of sulphuric acid and nitric acid formed from pollutants is called acid rain.
- What is marble cancer?
Answer – The slow corrosion of marble structures due to acid rain is known as marble cancer.
Long Answer Questions
- How does burning fossil fuels contribute to air pollution and global warming?
Answer – Burning fossil fuels releases harmful gases like carbon dioxide, carbon monoxide, and sulphur dioxide. These gases cause air pollution, lead to acid rain, and increase greenhouse gas concentrations, thus contributing to global warming.
- Describe the greenhouse effect. What are its causes and consequences?
Answer – The greenhouse effect is the trapping of heat radiations by gases like carbon dioxide, methane, and water vapour, causing the earth’s temperature to rise.
Causes: Burning fossil fuels, deforestation, agriculture.
Consequences: Global warming, rising sea levels, melting glaciers, severe heatwaves.
- List five methods to control air pollution.
Answer – Use of smokeless chulhas and solar cookers.
Using CNG and unleaded petrol in vehicles.
Installation of tall chimneys with filters.
Planting more trees.
Avoiding the burning of crackers.
MCQs (Multiple Choice Questions)
- Which of the following is a greenhouse gas?
- a) Oxygen
- b) Nitrogen
- c) Methane
- d) Argon
Answer – Answer: c) Methane
- Which pollutant is mainly responsible for the depletion of the ozone layer?
- a) Carbon dioxide
- b) Carbon monoxide
- c) Chlorofluorocarbons
- d) Sulphur dioxide
Answer – Answer: c) Chlorofluorocarbons
- Acid rain is caused by the presence of which acids?
- a) Hydrochloric and sulphuric acids
- b) Sulphuric and nitric acids
- c) Nitric and hydrochloric acids
- d) Citric and sulphuric acids
Answer – Answer: b) Sulphuric and nitric acids
- Which of the following gases is formed by incomplete combustion of fuels?
- a) Carbon dioxide
- b) Nitrogen dioxide
- c) Carbon monoxide
- d) Methane
Answer – Answer: c) Carbon monoxide
- The harmful complex formed by carbon monoxide and haemoglobin is—
- a) Haemoglobin oxide
- b) Carboxyhaemoglobin
- c) Carbon nitrate
- d) Nitric haemoglobin
Answer – Answer: b) Carboxyhaemoglobin
True/False
- The Taj Mahal is being affected by marble cancer.
Answer – True
- Chlorofluorocarbons help in protecting the ozone layer.
Answer – False
- Greenhouse gases trap the heat reflected by the Earth’s surface.
Answer – True
- Smog formation is a problem only in summers.
Answer – False (mainly in winters)
- Acid rain enhances the fertility of the soil.
Answer – False
Assertion and Reason Type Questions
Assertion: The greenhouse effect is a natural phenomenon that helps keep the Earth warm.
Reason: Greenhouse gases trap heat radiations that are reflected by the Earth’s surface.
Answer: Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
Assertion: Smog is harmful to human health.
Reason: Smog is formed when smoke combines with fog and other pollutants.
Answer: Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
Assertion: Carbon dioxide is the major gas responsible for the depletion of the ozone layer.
Reason: Ozone layer is destroyed by chlorofluorocarbons (CFCs), not carbon dioxide.
Answer: Assertion is false, but Reason is true.
Assertion: Acid rain corrodes marble and limestone monuments.
Reason: Acid rain contains sulphuric and nitric acids that dissolve marble and limestone.
Answer: Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
Assertion: Global warming leads to a rise in the sea level.
Reason: Melting of glaciers due to the warming atmosphere causes the sea level to rise.
Answer: Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
Fill in the Blanks
- The main source of nitrogen dioxide in the atmosphere is _________.
Answer: combustion of petrol in automobiles.
- ________ is the phenomenon caused by the trapping of heat radiations by certain gases in the atmosphere.
Answer: Greenhouse effect.
- The process of ________ is responsible for the formation of carboxyhaemoglobin.
Answer: Inhalation of carbon monoxide.
- ________ are gases that contribute to the depletion of the ozone layer.
Answer: Chlorofluorocarbons (CFCs).
- ________ is the term used for the slow corrosion of marble structures due to acid rain.
Answer: Marble cancer.
- ________ is the main greenhouse gas released from burning fossil fuels.
Answer: Carbon dioxide.
- The ________ effect is the rise in global temperatures due to an increase in greenhouse gases.
Answer: Global warming.
- ________ in air contributes to respiratory problems and can retard plant growth.
Answer: Nitrogen dioxide.
Match the Following
1.
Column A | Column B |
1. Carbon monoxide | a) Traps heat in the atmosphere |
2. Smog | b) Leads to respiratory problems and lung diseases |
3. Chlorofluorocarbons (CFCs) | c) Causes acid rain |
4. Greenhouse gases | d) Depletes the ozone layer |
5. Acid rain | e) Contributes to global warming |
Answer: 1 Answer – b) Leads to respiratory problems and lung diseases
2 Answer – c) Causes acid rain
3 Answer – d) Depletes the ozone layer
4 Answer – a) Traps heat in the atmosphere
5 Answer – c) Causes acid rain
2.
Column A | Column B |
1. Acid rain | a) Damages aquatic life and plants |
2. Greenhouse effect | b) Leads to global warming |
3. Smog | c) Forms when smoke mixes with fog |
4. Deforestation | d) Reduces carbon dioxide consumption |
5. Greenhouse gases | e) Contribute to the warming of the Earth’s atmosphere |
Answer: 1 Answer – a) Damages aquatic life and plants
2 Answer – b) Leads to global warming
3 Answer – c) Forms when smoke mixes with fog
4 Answer – d) Reduces carbon dioxide consumption
5 Answer – e) Contribute to the warming of the Earth’s atmosphere
Additional Questions and Answers – 02
Fill in the Blanks:
- The Latin word ______ means “to make dirty,” from which the term pollution is derived.
Answer: pollotioneum
- ______ is a deadly gas that caused the Bhopal gas tragedy.
Answer: Methyl isocyanate (MIC)
- The two main gases in the atmosphere are ______ (78%) and ______ (21%).
Answer: nitrogen, oxygen
- ______ is formed when smoke mixes with fog.
Answer: smog
- Acid rain contains ______ acid and ______ acid.
Answer: sulphuric, nitric
- The ______ layer protects Earth from harmful UV radiation.
Answer: ozone
- ______ is the phenomenon where greenhouse gases trap heat, leading to a rise in Earth’s temperature.
Answer: Greenhouse effect
- ______ is a major greenhouse gas released by burning fossil fuels.
Answer: Carbon dioxide (CO₂)
- ______ is an alternative fuel for vehicles that reduces air pollution.
Answer: CNG (Compressed Natural Gas)
- The ______ protocol aims to reduce greenhouse gas emissions globally.
Answer: Kyoto Protocol
- Match the Columns:
Column A (Pollutant) Column B (Harmful Effect)
Carbon monoxide (a) Depletes ozone layer
Nitrogen dioxide (b) Causes suffocation by binding to hemoglobin
CFCs (c) Leads to acid rain
Sulphur dioxide (d) Reduces photosynthesis in plants
Smog (e) Causes respiratory diseases like asthma
Answers:
1 – (b), 2 – (d), 3 – (a), 4 – (c), 5 – (e)
Assertion-Reason Questions:
Directions: Choose the correct option:
- Both Assertion (A) and Reason (R) are true, and R explains A.
- Both A and R are true, but R does not explain A.
- A is true, but R is false.
- A is false, but R is true.
- Assertion (A): Acid rain corrodes marble monuments like the Taj Mahal.
Reason (R): Marble reacts with sulphuric acid in acid rain to form soluble salts.
Answer: A (Both true; R explains A chemically).
- Assertion (A): CFCs are banned in refrigerators.
Reason (R): CFCs trap heat and cause global warming.
Answer: B (Both true, but R is incorrect—CFCs are banned for ozone depletion, not greenhouse effect).
- Assertion (A): Planting trees reduces global warming.
Reason (R): Trees absorb CO₂ during photosynthesis.
Answer: A (Both true; R explains A).
- Assertion (A): Smog is common in winters.
Reason (R): Cold air traps pollutants near the ground.
Answer: A (Both true; R explains A’s seasonal occurrence).
- Assertion (A): CNG is cleaner than diesel.
Reason (R): CNG releases more CO₂ per unit of energy.
Answer: C (A is true; R is false—CNG releases less CO₂).
(MCQs/True-False
MCQs:
- Which gas is not a greenhouse gas?
- a) CO₂
- b) Methane
- c) Oxygen ✅
- d) Nitrous oxide
- What is “marble cancer”?
- a) Fungal growth on marble
- b) Corrosion due to acid rain ✅
- c) Cracking from earthquakes
- d) Discoloration by UV rays
True/False:
Ozone layer depletion causes global warming. (False—it increases UV radiation, not heat).
Deforestation increases CO₂ levels in the atmosphere. (True—fewer trees mean less CO₂ absorption).
Nitrogen dioxide is harmless to plants. (False—it reduces photosynthesis).