Maharashtra Board Class 8 Science Chapter 8 Pollution Solutions

Question 1. Following are some statements about pollution. Which type of pollution do those express:
(a) Fog seems to be appearing in Delhi during day hours.
Answer: Air pollution-Smog (The sentence should have the word Smog and not fog. Smog is fog with smoke. Only fog cannot be polluting, but the smog is.)
(b) Many times, vomiting and dysentery occurs after eating 'panpuri'.
Answer: Water pollution-Contaminated food and water due to bacteria or virus
(c) Problem of sneezing occurs sometimes during visit to garden.
Answer: Air pollution due to pollens
(d) Crop does not grow up in some areas.
Answer: Soil pollution
(e) People living in the busy squares face the problems like short breathing and other respiratory problems.
Answer: Air pollution due to traffic
In simple words: This question identifies different types of pollution (air, water, soil) based on common real-world observations and their associated causes or effects.

🎯 Exam Tip: To score well, clearly identify the type of pollution and briefly explain the reason or pollutant associated with the given statement.

Question 2. Read the passage and identify the sentences expressing types of pollution.
(a) Nilesh is a student of Std. VII and lives in urban area. It takes about an hour to go to the school by bus. He faces the heavy traffic of two wheelers, four wheelers, rickshaws, buses while going to school. He is facing the problem of asthma since last few days, Doctors recommended him to stay away from urban area. Since then, his mother sent him to the village of his maternal uncle, Nilesh saw the heaps of garbage at many places in village. Foul smell of human and animal wastes was present at many places. Blackish water with foul smell was flowing in a stream. He developed some abdominal disease within few days.
Answer:
1. It takes about an hour to go to the school. (Due to traffic jam, Nilesh is spending more time in polluted, contaminated air.)
2. He faces the heavy traffic. (Large scale combustion of fossil fuel.)
3. He is facing the problem of asthma. (Air pollution - Harmful to human health.)
4. The heaps of garbage at many places. (Solid waste - Land pollution.)
5. Foul smell of human and animal wastes. (Biological pollution, air pollution.)
6. Blackish water with foul smell was flowing in a stream. (Improper sewage management - Water pollution.)
7. He developed some abdominal disease within few days. (Water pollution - Effect on human health.)
In simple words: This passage illustrates various forms of pollution such as air pollution from traffic and foul smells, land pollution from garbage, and water pollution from sewage, detailing their sources and impacts on human health.

🎯 Exam Tip: When analyzing a passage, break it down sentence by sentence and connect specific events or observations to known types of pollution. Clearly state the pollution type and the underlying cause.

Question 3. Match the pairs from 'A' and 'B' columns and explain the effect of pollution on human health.
(a)

Answer:

In simple words: This question matches specific pollutants with their corresponding harmful effects on human health, highlighting how different contaminants can lead to various diseases and conditions.

🎯 Exam Tip: Memorize the specific health effects associated with common pollutants like heavy metals (cobalt, lead) and industrial gases (methane, sulphur dioxide, nitrogen dioxide) to correctly match them.

Question 4. True or false.
(a) Water does not get polluted by washing the clothes in running water of river.
Answer: False. (Even if washing of soiled clothes is done in running water, it will cause pollution as the dirt and the waste materials will be added to water. This certainly will cause water pollution.)
In simple words: Washing soiled clothes in a river, even running water, causes water pollution because dirt, detergents, and waste materials are released directly into the water body.

🎯 Exam Tip: When answering true/false questions, always provide a concise justification for your choice, explaining *why* a statement is true or false to demonstrate understanding.

Question 4. True or false.
(b) More the use of electric appliances, more will be the pollution.
Answer: True. (Most of the electricity is generated in India by burning coal. The power generation plants thus cause lots of air pollution. More the electricity is used by using more appliances, there will be more pollution. However, only power generation through solar energy cannot cause pollution.)
In simple words: Increased use of electric appliances generally leads to more pollution because a significant portion of electricity is generated by burning fossil fuels, which release harmful pollutants into the air.

🎯 Exam Tip: For environmental impact questions, consider the entire lifecycle, from energy generation to consumption, to identify hidden sources of pollution. Note exceptions like renewable energy sources.

Question 5. Answer the following:
(a) What is pollution?
Answer: Contamination of natural environment that can harmfully affect the environment is called pollution.
In simple words: Pollution is when harmful substances contaminate our natural surroundings, negatively impacting the environment and living organisms.

🎯 Exam Tip: A good definition of pollution includes both the idea of contamination and the resulting harmful effects on the environment or its inhabitants.

Question 5. Answer the following:
(b) What are Pollutants?
Answer: The products which affect the normal functioning of ecosystem and have an adverse effect on plants, animals and humans are called pollutants.
In simple words: Pollutants are the substances or agents that cause pollution by negatively affecting the ecosystem, including plants, animals, and humans.

🎯 Exam Tip: When defining pollutants, emphasize their adverse impact on the ecosystem's normal functioning and their broad effect on all forms of life.

Question 5. Answer the following:
(c) What is acid rain?
Answer:
1. When rainwater contains harmful amounts of nitric and sulphuric acids, it is called acid rain.
2. Burning of fossil fuels such as coal, wood, petroleum, etc. releases nitrogen oxide and sulphur oxide into the atmospheric air.
3. Since these oxides are soluble in water, they dissolve in rainwater. Nitrogen and sulphur oxides dissolved in large quantities of water vapour form acids like nitric acid, nitrous acid, sulphurous acid and sulphuric acid.
4. These acids mix with mist, drops of rainwater and snow. They change their composition and fall back on the ground in the form of acid rain.
5. Effects of acid rain are as follows:
• Increase in the acidity of soil and water bodies.
• Damage to the trees.
• Water becomes unsuitable for fish and wildlife.
• Buildings, statues, sculptures, bridges, monuments and fences are corroded due to acid rain. Thus, acid rain damages our national assets.
• Acid rain affects agriculture and crop lands.
In simple words: Acid rain is precipitation containing harmful nitric and sulphuric acids, formed when pollutants from burning fossil fuels dissolve in atmospheric water, causing damage to ecosystems, infrastructure, and agriculture.

🎯 Exam Tip: A comprehensive answer for acid rain should cover its definition (acids in rainwater), its formation (emission of oxides from fossil fuels), and its various environmental and structural impacts.

Question 5. Answer the following:
(d) What is greenhouse effect?
Answer:
1. Greenhouse effect is the ; phenomenon due to which global warming and climate change occur.
2. The earth receives solar energy in the form of heat from the sun. The surface of earth absorbs this heat and reflects it back to the atmosphere as infrared radiation. Some of this heat energy goes directly into space.
In simple words: The greenhouse effect is the natural process where certain atmospheric gases trap some of the sun's heat, warming the Earth's surface and leading to global warming and climate change.

🎯 Exam Tip: When explaining the greenhouse effect, clearly describe how solar energy is absorbed and re-radiated by the Earth, and how certain gases trap this heat, leading to temperature increases.

Question 5. Answer the following:
(e) Which are visible pollutants known to you?
Answer: The polluting substances that are seen easily with the naked eyes can be called as visible pollutants. E.g. Solid wastes, plastic articles, plastic bags, the suspended things in the water, metal refuse, etc.
In simple words: Visible pollutants are easily observable harmful substances like solid waste, plastics, and suspended particles in water.

🎯 Exam Tip: Provide clear, tangible examples of visible pollutants to illustrate your understanding of the concept.

Question 5. Answer the following:
(f) Which are invisible pollutants?
Answer: The pollutants which are completely dissolved in water or mixed in the air, cannot be seen and hence they can be called invisible pollutants. Since they are not seen, we remain unaware about the presence of these pollutants. E.g. the insecticides spread f on the crops. Aerosols, many hazardous gases in the air, toxic compounds that are totally soluble in water, etc.
In simple words: Invisible pollutants are harmful substances that cannot be seen because they are dissolved in water or mixed in the air, such as hazardous gases, aerosols, and soluble toxic compounds.

🎯 Exam Tip: Differentiate invisible pollutants from visible ones by highlighting their characteristic of not being seen, making them potentially more insidious, and give examples like gases or dissolved chemicals.

Question 6. Answer the following.
(a) Give two examples of each of water, soil and air pollution from your residential area.
Answer: Air pollution:
1. New buildings are constructed. Old structures are demolished. This is creating lots of dust pollution. The air is full of particulate matter.
2. The number of vehicles on the road has tremendously increased. This causes smoky environment.
Water pollution:
1. The sea shows lots of floating plastic and decaying flowers, etc. When beaches are visited it is a common sight.
2. Many fishes are seen dying in great numbers and are washed off to the shore.
Soil pollution :
1. Everywhere garbage heaps are seen. In that plastic bags, needles, old medicine vials and cartons are seen in abundance.
2. The sludge brought by rainwater is spread everywhere and that causes stink.
In simple words: Air pollution comes from dust and vehicle exhaust, water pollution from discarded waste and dead marine life, and soil pollution from visible garbage and smelly sludge.

🎯 Exam Tip: When asked for local examples, think about construction, traffic, waste disposal, and aquatic habits to provide relevant and specific illustrations for each pollution type.

Question 6. Answer the following.
(b) How does the pollution occur due to vehicles? Give the names of vehicles causing least pollution.
Answer:
1. More than 50% of the air pollution is caused by vehicular traffic.
2. Particulate matter, unburnt hydrocarbons, CO, nitrogen oxides and carcinogenic hydrocarbons are present in the automobile exhausts.
3. Fossil fuels like petrol, diesel, natural gas, gasoline, etc. which are burnt to run the automobiles lead to the emission of CO2 and other gases.
4. Therefore, vehicles are said to be the major contributors to air pollution.
5. The only vehicle which is non-polluting is bicycle. The four-wheelers which are battery operated are also manufactured recently.
These two types of vehicles are eco-friendly. The cars that run on C.N.G. are also said to be lesser polluting.
In simple words: Vehicles cause air pollution by burning fossil fuels, releasing harmful gases and particulate matter; bicycles and battery-operated vehicles are the least polluting options.

🎯 Exam Tip: Focus on the combustion of fossil fuels and the specific pollutants released by vehicle exhausts. Remember to mention eco-friendly alternatives like bicycles and electric vehicles for a complete answer.

Question 6. Answer the following.
(c) What are natural reasons causes for water pollution?
Answer: The natural causes of the water pollution:
1. If organic pollutants are added to the water there is an overgrowth of weeds such as Eichhornia. The growth of algae also makes the water unsuitable for consumption. These aquatic plants release oxygen during daytime but by night they require oxygen thus depleting the dissolved oxygen level. The natural characters of water are then changed.
2. The decomposing matter when added to the water make it polluted and stinking.
3. Due to deposition of sludge or eroded soil, the rivers change their path and divert from original flow. The currents are also changed. Deposition of sludge makes the water polluted.
4. Due to soil erosion, surrounding the water bodies, the microbes, bacteria, protozoans and the worms and larvae of nematodes enter the water causing severe biological pollution. Many inorganic pollutants are also added to the water. The fungand bacteria present in the water make it non-potable. Such water spreads water-borne diseases.
In simple words: Natural water pollution can occur due to excessive growth of aquatic plants, decomposition of organic matter, deposition of eroded soil or sludge, and the influx of microbes from soil erosion, leading to changes in water quality and spread of diseases.

🎯 Exam Tip: When discussing natural causes, distinguish between biological (e.g., algae, microbes) and physical/chemical (e.g., eroded soil, decomposing matter) factors that contribute to water degradation.

Question 6. Answer the following.
(d) Suggest four preventive measures for air pollution.
Answer: The following methods are adopted to control air pollution from the industries:
1. The source discharge is diluted by tall chimneys.
2. There are source correction methods like changing the raw material, equipment modification, process modification, etc.
3. Effective pollution controlling equipment like dust collectors, electrostatic precipitators, wet scrubbers, etc. should be used.
4. There should be ban and control over atomic tests and chemical weapons on the international level.
In simple words: Air pollution can be reduced by using tall chimneys for pollutant dispersion, modifying industrial processes, employing pollution control equipment like scrubbers, and enforcing international bans on atomic tests and chemical weapons.

🎯 Exam Tip: Focus on a range of solutions, including dispersal methods, source reduction, technological controls, and regulatory measures, to show a comprehensive understanding of air pollution prevention.

Question 6. Answer the following.
(e) Explain relation between greenhouse effect and global warming.
Answer: Because of greenhouse effect, there is increase in the global temperature. The heat on the earth remains trapped due to envelope of greenhouse gases. The percentage of carbon dioxide and methane is constantly increasing and hence there is increase in the temperature too. Thus the greenhouse effect is directly related to the global warming. Effects of this relation between greenhouse effect and global warming are as follows:
1. The polar ice caps and the glaciers at both the poles are melting due to increased temperature.
2. The oceans' water is rising due to this melted ice. The sea level rise is causing coastal land submergence. The islands at various regions are threatened of drowning.
3. Many species of living organisms are already extinct due to global warming. The rest are also threatened.
4. Wild animals are showing weird migrations. Polar bear is endangered.
5. The increased temperature of the oceanic water is causing many changes in the tides and currents. This results into increased occurrence of cyclones, hurricanes and cloud bursting. The natural disasters are rising in last decade.
6. The agricultural production is decreasing. The regions with less rainfall are facing draughts.
In simple words: The greenhouse effect is when atmospheric gases trap heat, causing global temperatures to rise, which is known as global warming. This warming leads to significant environmental changes like melting ice caps, rising sea levels, species extinction, and altered weather patterns.

🎯 Exam Tip: Clearly define both the greenhouse effect and global warming and then establish the cause-and-effect relationship between them. Support your explanation with multiple, diverse consequences of global warming.

Question 6. Answer the following.
(f) Construct two slogans each on air, water and soil pollution.
Answer: Air pollution:
1. Be a part of the solution and not part of pollution.
2. Show your care, clean your air.
Water pollution:
1. Water, water everywhere, Not a drop to drink. The pollution is making all the water stink.
2. Save the fish and the little turtle. Don't throw plastic or it will encircle.
Soil Pollution:
1. Don't be mean, keep environment clean.
2. Let's keep land clean, together only we can win.
In simple words: Slogans raise awareness about pollution, urging action for cleaner air, safeguarding water from waste, and keeping land free from contamination.

🎯 Exam Tip: Slogans should be short, catchy, and directly convey a message about prevention or the impact of pollution, appealing to environmental responsibility.

Question 7. Classify the following pollutants into natural and manmade categories.
Question Classify the following pollutants into natural and manmade categories. Sewage, dust, pollen grains, chemical fertilizers, vehicular smoke, algae, pesticides, waste of animals and birds.
Answer:

In simple words: Pollutants can be categorized based on their origin: natural sources like pollen and natural dust, or man-made sources such as sewage, vehicular smoke, and chemical pesticides.

🎯 Exam Tip: When classifying pollutants, consider whether the substance originates from human activities (man-made) or occurs independently in nature (natural) to ensure accurate categorization.

Project:

Question 1. Visit the water testing laboratory in your area and collect the information about tests for checking the purity of water.
Answer: [No direct answer provided in the source text. This is a project-based question requiring student research.]
In simple words: Students are tasked with visiting a local water testing lab to learn about methods used to check water purity, such as tests for pH, dissolved oxygen, bacteria, and chemical contaminants.

🎯 Exam Tip: For project-based questions, actively engage in research and field visits. Focus on understanding the practical application of scientific concepts and the methods used in real-world scenarios.

Rewrite the sentences after filling the blanks:

Question 1. Natural pollutants are destroyed in due course of time by .............
Answer: Natural pollutants are destroyed in due course of time by nature's rule.
In simple words: Natural pollutants eventually break down or dissipate over time through natural processes.

🎯 Exam Tip: Fill-in-the-blanks test knowledge of specific terms or concepts. Ensure the chosen word fits both grammatically and contextually.

Question 2. Air pollutants with ............. cause colour change in paints, oil paintings, nylon, etc.
Answer: Air pollutants with sulphur cause colour change in paints, oil paintings, nylon, etc.
In simple words: Sulphur compounds in the air react with and degrade materials like paints and fabrics, causing discoloration.

🎯 Exam Tip: Identify the specific chemical pollutants responsible for common forms of material degradation to answer accurately.

Question 3. Boards indicating the ............. are displayed in busy squares in metro cities.
Answer: Boards indicating the air quality index are displayed in busy squares in metro cities.
In simple words: Air quality index boards show the current level of air pollution in cities, informing the public about air conditions.

🎯 Exam Tip: Recognize common urban environmental monitoring tools and their purpose, such as air quality index displays.

Question 4. Soil ............ decreases due to pollution.
Answer: Soil fertility decreases due to pollution.
In simple words: Pollution diminishes the soil's ability to support plant growth by reducing its fertility.

🎯 Exam Tip: Understand the direct impacts of pollution on natural resources, such as soil becoming less productive.

Question 5. Problem of ............. pollution increases due to soil pollution.
Answer: Problem of water pollution increases due to soil pollution.
In simple words: Contaminated soil can release harmful substances into groundwater and surface water, thereby worsening water pollution.

🎯 Exam Tip: Consider the interconnectedness of different environmental compartments; soil pollution often leads to water pollution through leaching and runoff.

State whether the following statements are True or False. Explain your statement:

Question 1. Polluted water is responsible for diseases such as cholera, hepatitis, typhoid, skin diseases and diseases of the alimentary canal.
Answer: True. (The water sources if they are contaminated with biological pollutants such as bacteria, viruses or protozoans, can cause variety of water-borne diseases.)
In simple words: This statement is true because contaminated water, especially with biological agents, directly leads to various water-borne illnesses affecting digestion and skin.

🎯 Exam Tip: When evaluating true/false statements, focus on the direct cause-and-effect relationship presented and confirm it with your knowledge of common water-borne diseases and their origins.

Question 2. When water is mixed with natural or artificial unwanted material, the dissolved oxygen level of such water increases.
Answer: False. (When water is mixed with natural or artificial unwanted material, the dissolved oxygen level of such water decreases. This causes harm to the resident animals. However when aquatic weeds and algae outgrow in number it causes rise in oxygen only during day time.)
In simple words: This statement is false because the addition of pollutants typically reduces dissolved oxygen in water, harming aquatic life, though excessive plant growth can temporarily increase oxygen during the day.

🎯 Exam Tip: Remember that pollutants generally deplete dissolved oxygen in water, a key indicator of water quality. Be aware of nuances like temporary oxygen increases during photosynthesis by overgrown algae.

Question 3. Though any amount of pollutants are added to the soil, the toxic substances do not leach into water.
Answer: False. (The toxic substances added to the soil can leach in the groundwater and cause water pollution.)
In simple words: This statement is false; toxic pollutants in soil can seep into groundwater and surface water, causing water pollution.

🎯 Exam Tip: Understand the concept of leaching, where substances move from soil into water, illustrating the interconnectedness of soil and water pollution.

Identify the odd term:

Question 1. Industrialization, Population explosion, Mining, Vehicular transport, Dust storms.
Answer: Dust storms (All others are man-made causes environmental degradation.)
In simple words: Dust storms are a natural phenomenon, whereas industrialization, population explosion, mining, and vehicular transport are human activities that cause environmental degradation.

🎯 Exam Tip: To identify the odd term, classify each item based on a common characteristic (e.g., natural vs. man-made, cause vs. effect) and find the one that doesn't fit the group.

Question 2. Poisoning, asthma, Silicosis, respiratory diseases.
Answer: Silicosis (All others are effects of methane.)
In simple words: Silicosis is a lung disease caused by silica dust, while poisoning, asthma, and general respiratory diseases can be related to methane exposure.

🎯 Exam Tip: Understand the specific causes of different health conditions. Silicosis has a distinct cause (silica dust) compared to the broader impacts linked to methane or general pollution.

Question 3. Irritation of eyes, respiratory tract, excess mucus, mental weakness
Answer: Mental weakness (All other are effects of sulphur dioxide.)
In simple words: Eye irritation, respiratory tract issues, and excess mucus are common physical symptoms of sulphur dioxide exposure, whereas mental weakness is not a direct or primary effect.

🎯 Exam Tip: Familiarize yourself with the common symptoms and specific health effects associated with major air pollutants like sulphur dioxide to correctly identify unrelated outcomes.

Question 4. Volcanic eruption, Earthquake, Atomic explosion, Forest fires.
Answer: Atomic explosion (All others are natural causes of air pollution.)
In simple words: Volcanic eruptions, earthquakes, and forest fires are natural events that can cause air pollution, while an atomic explosion is a man-made event.

🎯 Exam Tip: Distinguish between natural phenomena that contribute to pollution and human-induced activities, particularly those with catastrophic environmental impacts.

Question 5. Uranium, Sulphur, Thorium, Plutonium.
Answer: Sulphur (All others are elements which are used in the production of atomic energy.)
In simple words: Uranium, thorium, and plutonium are radioactive elements crucial for atomic energy, while sulphur is a non-radioactive element primarily known for its role in acid rain and other chemical processes.

🎯 Exam Tip: Identify the common characteristic or application of the majority of terms (e.g., radioactive elements for atomic energy) to correctly single out the one that differs.

Consider the relation between the items in the first pair and write the correlation for second pair:

Question 1. Industrialization: Sulphur compounds ::........... : Lead compounds
Answer: Use of fuels/Transportation
In simple words: Just as industrialization is linked to sulphur compounds, the use of fuels and transportation is linked to lead compounds (historically from leaded gasoline).

🎯 Exam Tip: For correlation questions, determine the relationship in the first pair (e.g., source of pollutant) and apply the same logic to find the missing term in the second pair.

Question 2. City where smoke and soot caused it to be called black city: Petersburg :: Indian city where worst ever industrial accident has occurred :
Answer: Bhopal
In simple words: Petersburg was known as a "black city" due to industrial pollution, similar to how Bhopal is known for its tragic industrial accident.

🎯 Exam Tip: Recognize specific historical or environmental events and their associated locations, especially those related to pollution disasters.

Question 3. Arsenic and Cadmium : Inorganic water pollutants : : Weedicides and insecticides :
Answer: Organic water pollutants.
In simple words: Arsenic and Cadmium are inorganic water pollutants, whereas weedicides and insecticides are classified as organic water pollutants.

🎯 Exam Tip: Understand the classification of pollutants into inorganic (e.g., heavy metals) and organic (e.g., pesticides, hydrocarbons) categories based on their chemical composition.

Write definitions:

Question 1. Air pollution.
Answer: Contamination of air by toxic gaseous and particulate pollutants in concentration which is harmful to human beings and his surroundings is called air pollution.
In simple words: Air pollution is the presence of harmful gases and particles in the atmosphere at levels that negatively impact human health and the environment.

🎯 Exam Tip: A precise definition for air pollution includes mentioning both gaseous and particulate contaminants and their detrimental effects on health and surroundings.

Question 2. Water pollution.
Answer: When toxic and unwanted substances enter, dissolve or remain suspended in the water bodies deteriorating the quality of water and affecting the aquatic ecosystem, then it is known as water pollution.
In simple words: Water pollution occurs when harmful substances enter water bodies, reducing water quality and negatively impacting aquatic life and the ecosystem.

🎯 Exam Tip: A complete definition of water pollution highlights the introduction of harmful substances, the deterioration of water quality, and the adverse effects on the aquatic ecosystem.

Question 3. Soil pollution.
Answer: Soil pollution is the phenomenon caused due to natural or man-made causes, which occurs when there are changes in its physical, biological and chemical properties of the soil leading to decreased fertility due to either natural or man-made reasons.
In simple words: Soil pollution is the alteration of soil properties by natural or man-made factors, reducing its fertility and overall quality.

🎯 Exam Tip: When defining soil pollution, include both natural and man-made causes and emphasize the resulting changes in its physical, biological, and chemical properties, leading to reduced fertility.

Distinguish between the following:

Question 1. Degradable and Non-degradable pollutants:

In simple words: Degradable pollutants break down naturally over time, often with microbial help, and do not accumulate, sometimes releasing odors. Non-degradable pollutants do not break down, persist in nature, and tend to accumulate without odor from decomposition.

🎯 Exam Tip: When distinguishing, focus on the core difference: biodegradability. Provide contrasting characteristics like accumulation, microbial action, odor, and clear examples for each type.

Question 2. Industrial waste and Domestic waste:

Answer: The table above distinguishes between industrial and domestic waste.
In simple words: Industrial waste often includes non-degradable, toxic materials from factories, requiring official monitoring. Domestic waste is household garbage, largely biodegradable, and managed by individual responsibility.

🎯 Exam Tip: Understanding the differences between industrial and domestic waste is crucial for identifying sources of pollution and proposing effective management strategies in exams.

Give Scientific Reasons:

Question 1. Domestic sewage is harmful for all forms of life.
Answer: 1. Domestic sewage contains water 2. There are detergents and washing private vehicles. powders containing phosphate, which are used to soften the water. 3. These chemicals are harmful to aquatic animals. 4. They also contain disease. causing pathogenic bacteria and viruses. 5. Hence, domestic sewage is harmful for originating from kitchen, bathrooms, toilet, forms of In simple words: Domestic sewage contains harmful chemicals from detergents and disease-causing bacteria/viruses, making it dangerous for all living organisms if released untreated into water bodies.

🎯 Exam Tip: When explaining the harm of domestic sewage, remember to highlight both chemical pollutants (like phosphates) and biological contaminants (pathogens) for a complete answer.

Question 2. Use public transport instead of private vehicles.
Answer: 1. All the automobiles use fossil used to soften the water. fuels Burning of fossil fuels causes air pollution by gaseous pollutants as well as by particulates. 2. Toxic gases such as CO, CH4, SO2, etc. are emitted through automobile exhausts. 3. When each person uses private vehicles, the proportion of air pollution increases. 4. Instead, public transport helps to reduce air pollution it will also help to ease trafficams. 5. Therefore, as a role of citizen in pollution control, public transport should be used instead of private vehicles. In simple words: Public transport reduces air pollution because fewer vehicles on the road mean less burning of fossil fuels and fewer toxic gas emissions compared to everyone using private cars. It also helps reduce traffic congestion.

🎯 Exam Tip: For questions on pollution control, advocating for public transport is a strong point. Emphasize its dual benefit: reducing emissions and easing traffic.

Question 3. Due to agriculture, there can be a lot of air pollution.
Answer: 1. During agricultural practices, open field burning is done. Due to this burning there is emission of gases like SO2, CO2, CH4, CO and oxides of nitrogen along with large amounts of particulate matter. 2. In agricultural practices, pesticides used emit toxic chemicals. 3. Industrial farms pollute air by emitting foul odour and airborne pollutants. 4. When manure is decomposed, there is production of greenhouse gases. In simple words: Agricultural activities contribute to air pollution through burning crop residue, using pesticides that release toxic chemicals, emitting foul odors from industrial farms, and releasing greenhouse gases from decomposing manure.

🎯 Exam Tip: When listing agricultural sources of air pollution, include both direct emissions from burning/chemicals and indirect ones like greenhouse gases from decomposition for a comprehensive answer.

Question 4. A hole has been observed in the ozone layer in the stratosphere near Antarctica.
Answer: 1. Ozone layer depletion is mainly caused due to the action of CFC (Chlorofluorocarbon) molecules in the air. 2. Due to various increased activities of humans, the magnitude of air pollution has been increasing in the last few decades. 3. CFC molecules were used as coolants in refrigerators, freezers and air conditioners. 4. They were also present in industrial solvents, dry cleaning agents and hospital sterilants, aerosols and foam. Due to such enhanced use, much of the CFCs were liberated in the last few years. 5. CFC molecules are decomposed by ultraviolet rays which release chlorine and fluorine molecules. 6. Chlorine and fluorine react with the ozone resulting in a hole in the ozone layer present in the stratosphere. Therefore, a hole has been observed in the ozone layer in the stratosphere above Antarctica. In simple words: The ozone hole over Antarctica is caused by chlorofluorocarbons (CFCs) released from human activities. These CFCs break down in the atmosphere, releasing chlorine and fluorine atoms that destroy ozone molecules.

🎯 Exam Tip: For questions on ozone depletion, clearly link human use of CFCs to their breakdown by UV rays, leading to the release of ozone-destroying chlorine and fluorine atoms.

Answer The Following:

Question 1. What do you mean by ozone layer depletion? What are the causes of ozone layer depletion?
Answer: 1. The ozone layer is present at the top of the stratosphere. The stratosphere is the second layer of the atmosphere which is present 48 km above the earth's surface. 2. Ozone layer is protective layer for living organisms of the earth, as it absorbs harmful UV rays from the sun. When this layer is reduced or destroyed, it is called ozone layer depletion. 3. Causes of the ozone layer depletion: 1. The main cause of ozone depletion are CFC molecules. 2. Chlorine atoms are present in chlorofluoro-carbons (CFC) molecules. They react with ozone and deplete it. 3. CFCs are used as coolants in refrigerators, freezers and air conditioners manufactured before 1995. 4. CFCs are also present in industrial solvents, dry cleaning agents and hospital sterilants (sterilizers), aerosols and foam. All the above materials release a lot of CFCs into the atmosphere. 5. CFC molecules are broken down by ultraviolet radiations which result in release of chlorine and fluorine, which further reduce the ozone layer. In simple words: Ozone layer depletion is the thinning of the protective ozone layer in the stratosphere, which shields Earth from harmful UV rays. It's primarily caused by human-made chlorofluorocarbons (CFCs), which release chlorine and fluorine atoms that destroy ozone molecules.

🎯 Exam Tip: Define ozone layer depletion by explaining its location and function, then detail the role of CFCs, their sources, and how they chemically break down ozone for a complete answer.

Question 2. What adverse effect does ozone depletion have?
Answer: 1. When the ozone layer is depleted, the ultraviolet radiations of the sun can reach the earth's surface in greater proportion. 2. This results in damage to animal and plant life on the earth. 3. Ultraviolet rays cause skin cancer and cataract in human beings. 4. The ozone hole is seen in the stratosphere above Antarctica. In simple words: Ozone depletion allows more harmful ultraviolet (UV) radiation from the sun to reach Earth, leading to increased rates of skin cancer and cataracts in humans, and causing damage to both plant and animal life.

🎯 Exam Tip: Focus on the direct consequence of ozone depletion - increased UV radiation - and its specific detrimental effects on human health (skin cancer, cataracts) and ecosystem damage.

Question 3. Describe the effects of air pollution on animals and plants.
Answer: 1. Effects of air pollution on animals: • Air pollutants affect breathing of the animals. • Particulate pollutants can cause problems to the wildlife. • Particulate matter containing heavy metals is accumulated in the bodies of animals. The accumulated heavy metals at high levels in the body tissues, can cause problems. ' • Acid rain causes serious problems to animal life. 2. Effects of air pollution on plants: • Various parts of the plant show reduced growth after coming in contact with air pollutants. • The leaves show yellowing or chlorosis on exposure to air pollutants. In simple words: Air pollution harms animals by causing respiratory issues, accumulating toxic heavy metals in their tissues, and leading to problems like acid rain. For plants, it stunts growth and causes leaves to yellow.

🎯 Exam Tip: When describing effects on animals and plants, categorize them (e.g., respiratory, bioaccumulation for animals; growth, leaf damage for plants) and mention specific pollutants if relevant (e.g., heavy metals, acid rain).

Question 4. What are man-made reasons for water pollution?
Answer: The effluents and other substances released by man into the surrounding water bodies together can be called man-made reasons for water pollution. 1. Domestic sewage: The excreta, urine and other domestic-use water is added to the water bodies in many cities and villages. In big metro-cities, the sewage is partially treated but these management practices are not enough. 2. Industrial effluent: Different industries and factories release effluents which may contain toxic and harmful components, such as various pigments, bleaching chemicals, leather pieces, fibres, mercury, lead, etc. 3. Oil pollution: Oil spillages are seen in the seas due to leakage of crude oil. The crude oil is hazardous as it contains cancer causing hydrocarbons. 4. Fertilizers and pesticides: These compounds when used in farm, may get washed off to nearby water body. The chemical fertilizer containing N, P, K cause water pollution. Pesticides such as endrin, chlorine, carbonate containing pesticides, etc. are mixed with water. They cause contamination of the aquatic animals. In simple words: Man-made water pollution comes from domestic sewage, untreated industrial waste containing toxic chemicals, oil spills, and agricultural runoff carrying fertilizers and pesticides into water bodies.

🎯 Exam Tip: List a variety of man-made sources, from household waste (sewage) to industrial discharges, oil spills, and agricultural chemicals, to show a comprehensive understanding.

Question 5. What are the effects of water pollution on human beings?
Answer: The water-borne diseases that are caused by different bacteria and viruses cause infections to human beings through contaminated water. Some bacterial and viral diseases are spread through epidemics. Cholera, hepatitis, enteritis, diarrhoea, typhoid are such diseases that can cause severe infections to man. Polluted water also cause skin diseases and deformities of bones, Some pollutants accumulated in vital organs cause their ailments. Liver, kidneys, brain, etc. are affected in this way. Person may develop hypertension too due to pollutants. In simple words: Water pollution causes various water-borne diseases like cholera and typhoid due to bacteria and viruses. It can also lead to skin diseases, bone deformities, and damage vital organs like the liver, kidneys, and brain due to the accumulation of toxic pollutants.

🎯 Exam Tip: When describing effects on humans, highlight both infectious diseases caused by pathogens and long-term health issues from chemical accumulation and organ damage.

Question 6. What are the effects of water pollution on the ecosystem?
Answer: Biological effects: 1. Plants in the ecosystem show retarded growth, resulting into species loss. 2. Due to imbalance in the ecosystem, the food chain and food web is disturbed. 3. Pollutants cause mortality in fish and other aquatic animals. 4. Oil slick causes harmful impact on the marine birds. 5. Useful bacterial fauna in the water is lost. Abiotic effects: 1. Pollutants cause changes in physical and chemical properties of water. 2. Salinity of the water changes. In simple words: Water pollution disrupts ecosystems by causing stunted plant growth and species loss, disturbing food chains, and killing aquatic animals. It also alters the water's physical and chemical properties, like salinity, harming the overall balance.

🎯 Exam Tip: Differentiate between biological effects (impact on living organisms, food webs) and abiotic effects (changes in water properties) for a structured and clear answer on ecosystem impact.

Question 7. Describe the effects of air pollution on the environment.
Answer: Air pollution can cause the following serious effects on the environment: 1. Deforestation and fuel consumption bring about rise in CO2 concentration. 2. Excess CO2 in air causes rise in atmospheric temperature of the earth. 3. The increased temperature is called global warming. 4. The global warming results into melting of glaciers, subsequently causing rise in the sea level. 5. There is a change in the climate and pattern of rainfall. This may indirectly affect the agricultural production. In simple words: Air pollution increases CO2, leading to global warming, which melts glaciers, raises sea levels, and alters climate and rainfall patterns, ultimately impacting agriculture.

🎯 Exam Tip: When explaining environmental effects, trace the chain of events from increased CO2 to global warming, glacier melt, sea level rise, and climate change for a logical flow.

Question 8. Describe the effects of soil pollution.
Answer: Effect of soil pollution: 1. There are many pathogenic bacteria, viruses and parasitic intestinal worms in the sewage sludge. These are able to cause many diseases. 2. Soil and vegetable crops are contaminated by manure made from human and animal excreta containing pathogens. This can lead to various diseases. 3. There is loss of fertility and productivity of soil and land due to soil pollution. 4. Soil pollution leads to water pollution, when toxic chemicals leach into the groundwater. Similarly, when contaminated soil enters into streams or lakes, it also causes water pollution. 5. Radioactive materials and soil contaminants can travel through food chains. They move away from the soil into crops, livestock and human bodies. In simple words: Soil pollution spreads diseases through pathogens in sewage and contaminated manure, reduces soil fertility, and causes water pollution when toxic chemicals leach into groundwater or runoff into surface water. Pollutants like radioactive materials can also enter the food chain.

🎯 Exam Tip: Highlight both direct effects (disease, fertility loss) and indirect effects (water pollution, food chain contamination) when discussing soil pollution's impact.

Question 9. How do biodegradable and non- biodegradable wastes cause land pollution?
Answer: 1. Biodegradable material is mainly present in the domestic waste. 2. It is in the form of food waste, peels of fruits, vegetables, etc. 3. Paper is also a main part of the domestic waste which is biodegradable. 4. Polythene bags, plastic waste and footwear, etc. are non-biodegradable waste from the domestic sources. All of these pollute the land. In simple words: Biodegradable wastes, like food scraps and paper, cause land pollution as they decompose and release foul odors and pathogens. Non-biodegradable wastes, such as plastic and footwear, accumulate indefinitely, physically degrading the land and blocking natural processes.

🎯 Exam Tip: Distinguish how each type of waste causes pollution: biodegradable through decomposition and associated issues, non-biodegradable through persistence and accumulation.

Question 10. How do you protect soil from being polluted?
Answer: 1. We should not throw domestic waste and industrial waste indiscriminately on the land, so that it contaminates soil. 2. Proper disposal of solid wastes and more importantly safe disposal of biomedical waste material should be practised. 3. Instead of throwing non-biodegradable materials on the land, they should be properly recycled and reused. 4. Biodegradable materials should be composted and converted into useful manure, rather than throwing them to cause pollution of the soil. 5. Excessive use of fertilizers and pesticides should be avoided so that the soil does not get contaminated. In simple words: To protect soil from pollution, we must properly dispose of all wastes, especially biomedical. Non-biodegradable items should be recycled, biodegradable items composted, and the overuse of fertilizers and pesticides avoided.

🎯 Exam Tip: Focus on practical, actionable measures: responsible disposal, recycling/composting, and reducing chemical use for a comprehensive answer on soil protection.

Question 11. What are the different laws to prevent pollution?
Answer: The different laws to prevent pollution are as follows: 1. Water (Prevention and Control of Pollution) Act, 1974. 2. Air (Prevention and Control of Pollution) Act, 1981. 3. Environment (Protection) Act, 1986. 4. There are different laws and rules which have been made for the disposal of hazardous waste, biomedical waste, solid waste and prevention of noise pollution. In simple words: India has specific laws to prevent pollution, including the Water Act (1974), Air Act (1981), and Environment Protection Act (1986). Additionally, various rules govern the disposal of hazardous, biomedical, and solid waste, as well as noise pollution.

🎯 Exam Tip: Listing specific acts with their years (e.g., Water Act 1974, Air Act 1981, Environment Protection Act 1986) demonstrates strong knowledge of regulatory frameworks for pollution control.

Question 12. Who implements the laws related to pollution?
Answer: The Central Pollution Control Board (CPCB) and Maharashtra Pollution Control Board (MPCB) check whether the organizations like factories, industrial estates, Municipalities, Zilla Parishads, Panchayat Samities and Gram Panchayats follow all the laws related to control of pollution. In simple words: The Central Pollution Control Board (CPCB) and Maharashtra Pollution Control Board (MPCB) are responsible for enforcing pollution laws by monitoring compliance among factories, industries, municipalities, and local government bodies.

🎯 Exam Tip: Remember to name the key regulatory bodies (CPCB and MPCB) and specify the types of organizations they oversee for pollution law compliance.

Use Your Brain Power!

Question 1. Which types of pollutants are observed?
Answer: Pollutants are of many varied types. They can be classified according to their sources, according to which ecosystem they are polluting, and according to their characteristics. In simple words: Pollutants vary widely and are categorized based on their origin, the environment they contaminate, and their inherent properties.

🎯 Exam Tip: When discussing types of pollutants, mentioning classification criteria like source, ecosystem affected, and characteristics shows a structured understanding rather than just listing examples.

Question 2. Whether the pollutants are degradable or non-degradable?
Answer: Some pollutants are biodegradable while some are non-biodegradable. The pollutants that spread in the air are in the form of gases or particulate matter. Though they are non-degradable, they constantly make chemical reactions with each other. The pollutants thrown in water and on land are of both the types. Pollutant like plastic is totally non-biodegradable. The biodegradable substances can be decomposed by various bacteria and fungand are converted back into elemental form. The pollutants added in S the water are also of two types. The heavy metals and colours are non-degradable. In simple words: Pollutants can be either biodegradable, meaning they naturally break down, or non-biodegradable, meaning they persist in the environment. Air pollutants are often non-degradable gases or particulates, while water and land can contain both types, with plastics and heavy metals being key non-degradable examples.

🎯 Exam Tip: Clearly define and provide examples for both biodegradable and non-biodegradable pollutants, noting how they behave differently in the environment.

Question 3. Whether the vehicles with two- stroke engine cause more pollution than four stroke engine?
Answer: Yes, they do. Scooters and motor cycles are more dominant source of air pollution as they emit soot and organic particles. In urban areas this proportion is high. These particles are toxic and they create heavy air pollution. The two-wheelers have two-stroke engines. Such engines are far less efficient in burning the fuel that is used in the vehicles. The exhaust systems are also less effective at removing pollutants. On the contrary most of the four-wheelers have catalytic converters. Therefore, the exhaust fumes from scooters contain higher levels of the chemicals found in the fuel and oil they use. The vehicles with two-stroke engine such as two wheelers emit significantly more primary organic aerosols and volatile organic compounds from incomplete burning of the fuel. They also produce significant secondary organic aerosols as gases released from the exhaust react with the air and microscopic particles of soot. These pollutants increase the risk of heart and lung disease. Older two-stroke vehicles produced reactive oxygen molecules that are known to be potentially harmful for lung health. In recent times there is excessive use of two-wheelers which is deteriorating the air quality to great extent. In simple words: Yes, two-stroke engines cause more pollution than four-stroke engines because they burn fuel less efficiently and lack catalytic converters, leading to higher emissions of soot, organic particles, and volatile compounds that are harmful to health and air quality.

🎯 Exam Tip: When comparing engine types, focus on fuel efficiency, presence of emission control systems (like catalytic converters), and the specific types of pollutants (soot, organic aerosols) each emits.

Question 4. Give 5 examples of each of domestic waste, biological waste and agricultural waste and write in your own words about soil pollution due to those wastes.
Answer: Domestic waste: 1. Empty containers of medicines, papers, bottles, etc. 2. Plastic 3. Glass pieces 4. Old utensils, clothes 5. Tins and cartons of used items, the discarded household items. Biological waste: 1. Dead corpse of animals. 2. Urine and faeces 3. Peels of fruits, stalks of vegetables and fruits. 4. Food waste 5. Garlands and old bouquets. Agricultural waste: 1. The stubs of crops after the grains are removed. 2. Cattle dung and urine 3. Some persistent amount of insecticides 4. Some amount of fertilizers 5. Empty containers, bags, cartons of insecticide, chemical fertilizers, seeds, gunny bags, etc. In simple words: Domestic waste like plastics and old items, biological waste such as animal corpses and food scraps, and agricultural waste including crop residue and chemical containers, all contribute to soil pollution by either accumulating non-degradable materials or releasing harmful substances during decomposition, reducing soil quality and fertility.

🎯 Exam Tip: Provide clear and distinct examples for each waste category. For the "In simple words" explanation, synthesize how *all* these wastes collectively impact soil pollution, highlighting both accumulation and decomposition aspects.

Diagram Based Questions:

Question 1. Given below is a diagram showing hazardous polluting event. Explain what is this and what are its effects shown in the diagram.
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र अम्लीय वर्षा की प्रक्रिया और उसके प्रभावों को दर्शाता है। इसमें औद्योगिक चिमनियों से SO2, NO2, CO2 जैसे ऑक्साइड निकलते हुए दिखाए गए हैं, जो वायुमंडल में मिलकर एसिड (अम्ल) बनाते हैं और फिर अम्लीय वर्षा के रूप में जमीन पर गिरते हैं। इससे जानवरों और पौधों को नुकसान होता है, जैसा कि चित्र में दर्शाया गया है।
Answer: The above picture depicts the formation and effects of acid rain. The toxic gases such as SO2, CO2 and NO2 are released through the chimneys of factories. These oxides are released in air. They get dissolved in the rainwater and reach back the earth's surface in the form of acids. The plants, animals and houses are being damaged due to this acid rain. In simple words: The diagram illustrates acid rain, which occurs when factories release toxic gases like SO2, CO2, and NO2. These gases mix with rainwater to form acids, falling back to Earth and causing damage to plants, animals, and structures.

🎯 Exam Tip: When explaining diagrams related to acid rain, clearly identify the source of pollutants (factories), the gases involved (SO2, NO2, CO2), the process of acid formation, and the resulting damage to the environment.

Question 2. Draw a well labelled diagram to show greenhouse effect.
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र ग्रीनहाउस प्रभाव को दर्शाता है। इसमें सूर्य से आने वाली ऊर्जा को वायुमंडल और पृथ्वी की सतह द्वारा अवशोषित किया जाता है। पृथ्वी से उत्सर्जित अवरक्त विकिरण (Infrared radiation) भी वायुमंडल में फंस जाती है, जिससे पृथ्वी का तापमान बढ़ जाता है, जो ग्रीनहाउस प्रभाव कहलाता है।
Answer: [Diagrams are not rendered directly. The textual explanation above serves as the answer.] In simple words: The greenhouse effect is when certain gases in Earth's atmosphere trap heat from the sun, preventing it from escaping back into space and thereby warming the planet, much like a greenhouse.

🎯 Exam Tip: When asked to explain the greenhouse effect via a diagram, remember to describe the absorption of solar energy by Earth and the trapping of infrared radiation by atmospheric gases.

Activity Based Questions:

Question 1. Discuss the issues like 'dry waste-wet waste' and 'toilet in each home' and write information in your own words.
Answer: In simple words: The "dry waste-wet waste" issue refers to the importance of segregating waste at source for better recycling and composting, while "toilet in each home" addresses public health and hygiene by ensuring proper sanitation facilities to prevent disease.

🎯 Exam Tip: For activity-based questions, emphasize practical solutions and their broader societal and environmental benefits. For waste, highlight segregation; for toilets, focus on hygiene and disease prevention.

MCQs Based On Practical:

Question 1. Which fertilizers when used in excessive amounts cause soil pollution that spreads to neighbouring water bodies and cause water pollution too?
(a) Chemical
(b) Organic
(c) Artificial
(d) Compost
Answer: (a) Chemical In simple words: Chemical fertilizers, when overused, seep into the soil and runoff into nearby water, causing both soil and water pollution.

🎯 Exam Tip: Recognize that excessive use of chemical fertilizers is a primary cause of both soil and water pollution due to leaching and runoff.

Question 2. What is the type of pollutants that are present in the industrial effluents that is released in the rivers and sea?
(a) Inorganic
(b) Organic
(c) Biological
(d) Biomedical
Answer: (a) Inorganic In simple words: Industrial effluents often contain inorganic pollutants like heavy metals and chemicals that are released into rivers and seas.

🎯 Exam Tip: Industrial effluents are typically characterized by inorganic pollutants such as heavy metals and various chemicals, which are non-biodegradable and highly toxic.

Question 3. What grows in excess when eutrophication of the water bodies take place?
(a) Plants
(b) Algae
(c) Fishes
(d) Fungi
Answer: (b) Algae In simple words: Eutrophication is the excessive growth of algae in water bodies, often caused by nutrient overload.

🎯 Exam Tip: Eutrophication is specifically linked to the rapid and excessive growth of algae, leading to oxygen depletion in water bodies.

Question 4. Which of the following is seen in the polluted water body?
(1) flowers used in pooja
(2) fruits
(3) fishes
(4) aquatic insects
(5) plastic bags
(6) turtles
(7) thick growth of algae
(8) light blue colour of water
(9) cattle wading in water
(10) broken idols
(a) (1) (3) (5) (6) (9) (10)
(b) (1) (2) (5) (7) (9) (10)
(c) (1) (3) (6) (8) (9) (10)
(d) (1) (2) (4) (7) (8) (9)
Answer: (b) (1) (2) (5) (7) (9) (10) In simple words: Polluted water bodies typically show signs like discarded religious offerings (flowers, broken idols), food waste (fruits), plastic bags, thick algal growth, and cattle wading in the water.

🎯 Exam Tip: When identifying signs of water pollution, look for visible debris (plastic, religious items), organic matter (fruits, algae growth), and human/animal activities (cattle wading) that directly contribute to contamination.

Question 5. Which is the easiest method to identify the polluted water?
(a) To taste the water
(b) To check the depth of water
(c) To observe colour and odour of the water
(d) To swim in the water
Answer: (c) To observe colour and odour of the water In simple words: The quickest and safest way to initially detect polluted water is by noticing abnormal changes in its color or smell.

🎯 Exam Tip: Simple sensory observations like unusual color or foul odor are often the most immediate indicators of water pollution, though not conclusive for all types.

Formative Evaluation:

Question 1. Which factors are responsible for pollution shown in the following pictures?
ℹ️ चित्र व्याख्या (Diagram Explanation): इस चित्र में वायु प्रदूषण के विभिन्न कारकों को दर्शाया गया है: बाईं ओर जंगल की आग (Forest fires), बीच में ज्वालामुखी विस्फोट (Volcanic eruption) और दाईं ओर वाहनों से होने वाला प्रदूषण (Vehicular traffic) दिखाया गया है। ये सभी वायुमंडल में हानिकारक गैसें और कण छोड़ते हैं।
Answer: Air pollution due to different factors In simple words: The pictures illustrate air pollution caused by factors such as forest fires, volcanic eruptions, and vehicular emissions, all of which release harmful substances into the atmosphere.

🎯 Exam Tip: When analyzing images for pollution causes, categorize them into natural (volcanic eruptions, forest fires) and man-made (vehicular traffic) sources.

Question 2. Compare the two neighbouring photographs.
ℹ️ चित्र व्याख्या (Diagram Explanation): इस चित्र में दो पड़ोसी दृश्यों की तुलना की गई है। बाईं ओर एक उपजाऊ, हलकी हुई मिट्टी वाला खेत (fertile, tilled soil) दिखाया गया है, जो स्वस्थ कृषि भूमि का प्रतीक है। दाईं ओर एक बंजर या प्रदूषित भूमि (barren or polluted land) दिखाई गई है, जिसमें मिट्टी अनुपयोगी और क्षतिग्रस्त प्रतीत होती है, संभवतः प्रदूषण या अपरदन के कारण।
Answer: [The OCR only provides the question, not the expected answer text. I will provide a placeholder answer and simple words/exam tip based on the implicit meaning of "compare photos" for pollution.] In simple words: The first photograph likely shows healthy, fertile soil, perhaps well-cultivated, while the second photograph probably depicts polluted or degraded soil, characterized by visible waste, lack of vegetation, or discoloration, indicating a loss of fertility.

🎯 Exam Tip: When comparing images of environmental conditions, focus on visual cues such as vegetation density, soil color and texture, presence of waste, and signs of erosion to infer pollution or degradation levels.

Formative Evaluation:

Question 1. Which factors are responsible for pollution shown in the following pictures?

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र वायु प्रदूषण के विभिन्न स्रोतों को दर्शाता है। इसमें जंगल की आग से निकलने वाला धुआँ, ज्वालामुखी विस्फोट से निकलने वाली राख और गैसें, तथा वाहनों के धुएँ से होने वाला प्रदूषण शामिल है, जो पर्यावरण और स्वास्थ्य पर हानिकारक प्रभाव डालते हैं।

Question 2. Compare the two neighbouring photographs.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र दो अलग-अलग प्रकार की भूमि को दर्शाता है। एक में खेती योग्य जुताई की गई मिट्टी दिख रही है, जबकि दूसरा चित्र पथरीली या अनुपजाऊ भूमि को दर्शाता है, संभवतः प्रदूषण या अपरदन के कारण।

MCQs Based On Practical:

Question 1. Which fertilizers when used in excessive amounts cause soil pollution that spreads to neighbouring water bodies and cause water pollution too?
(a) Chemical
(b) Organic
(c) Artificial
(d) Compost
Answer: (a) Chemical
In simple words: Excessive use of chemical fertilizers pollutes the soil and, by washing into water bodies, also causes water pollution.

🎯 Exam Tip: Focus on identifying the primary and secondary impacts of common pollutants like chemical fertilizers.

Question 2. What is the type of pollutants that are present in the industrial effluents that is released in the rivers and sea?
(a) Inorganic
(b) Organic
(c) Biological
(d) Biomedical
Answer: (a) Inorganic
In simple words: Industrial waste often contains inorganic pollutants like heavy metals that are released into rivers and seas.

🎯 Exam Tip: Remember the specific types of pollutants associated with industrial waste, particularly those affecting water bodies.

Question 3. What grows in excess when eutrophication of the water bodies take place?
(a) Plants
(b) Algae
(c) Fishes
(d) Fungi
Answer: (b) Algae
In simple words: Eutrophication, caused by nutrient enrichment, leads to an excessive growth of algae in water bodies.

🎯 Exam Tip: Understand the process of eutrophication and its direct impact on aquatic life, particularly the proliferation of algae.

Question 4. Which of the following is seen in the polluted water body?
(1) flowers used in pooja
(2) fruits
(3) fishes
(4) aquatic insects
(5) plastic bags
(6) turtles
(7) thick growth of algae
(8) light blue colour of water
(9) cattle wading in water
(10) broken idols
(a) (1) (3) (5) (6) (9) (10)
(b) (1) (2) (5) (7) (9) (10)
(c) (1) (3) (6) (8) (9) (10)
(d) (1) (2) (4) (7) (8) (9)
Answer: (b) (1) (2) (5) (7) (9) (10)
In simple words: Polluted water bodies often show debris like flowers, fruits, plastic bags, thick algal growth, presence of cattle, and broken idols.

🎯 Exam Tip: Be able to identify common visual indicators of water pollution from various sources.

Question 5. Which is the easiest method to identify the polluted water?
(a) To taste the water
(b) To check the depth of water
(c) To observe colour and odour of the water
(d) To swim in the water
Answer: (c) To observe colour and odour of the water
In simple words: The simplest way to detect polluted water is by noticing abnormal changes in its colour or by its foul smell.

🎯 Exam Tip: Recognize basic sensory indicators for identifying polluted water without specialized equipment.