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Social Issues and Environment: AHSEC Class 11 Environment
Get summay, questions, answers, solutions, notes, extras, PDF, competency-based questions of chapter- 6/unit I, Social Issues and Environment: AHSEC Class 11 Environmental Education, which is part of the present syllabus. These solutions, however, should only be treated as references and can be modified/changed.
If you notice any errors in the notes, please mention them in the comments
Summary
Growing populations and industries have placed great strain on our planet’s natural resources, like land and water. This has led to a decline in environmental quality. To address this, the idea of sustainable development was introduced. Sustainable development means meeting our current needs without preventing future generations from meeting their own. It is about finding a balance between economic growth and protecting the environment. This concept gained attention after a report called “Our Common Future” was published in 1987 and was further discussed at the 1992 Earth Summit.
Development requires a lot of energy. Energy is the power to do work. There are two main types of energy sources. Renewable sources are those that do not run out, such as solar, wind, and hydropower. Non-renewable sources are limited and will eventually be used up, like coal, petroleum, and natural gas. Using too much energy, especially from non-renewable sources, can harm the environment. Energy conservation is the effort to reduce energy use. This can be done by using energy more efficiently and switching to renewable sources. Conserving energy helps protect the planet and can reduce global warming.
Water is another precious resource. Rainwater harvesting is a method of collecting and storing rainwater from rooftops and open spaces. This stored water can be used later, which reduces the demand on groundwater. It is a simple technique that helps manage water supplies, especially in areas with irregular rainfall. A clean environment is also necessary for good health. The World Health Organization states that health is a state of complete physical, mental, and social well-being. Polluted water can cause many diseases. Air pollution from industries and vehicles also poses serious health risks.
Our planet is kept warm by a natural process called the greenhouse effect. Gases in the atmosphere, like carbon dioxide, trap some of the sun’s heat, acting like a blanket to keep Earth at a comfortable temperature for life. However, human activities have released too many of these gases, making the blanket thicker. This traps too much heat and causes the Earth’s temperature to rise, a phenomenon known as global warming. This warming leads to climate change, which involves long-term shifts in weather patterns. Another environmental issue is the depletion of the ozone layer, a protective shield in the atmosphere that blocks harmful ultraviolet rays from the sun. Certain man-made chemicals called CFCs have damaged this layer. International agreements like the Montreal Protocol were created to stop the use of these harmful substances. Finally, pollution from burning fossil fuels can lead to acid rain, which occurs when pollutants mix with water in the atmosphere and fall to the ground, harming forests and lakes.
Textual/Exercise
1. What do you mean by sustainable development ?
Answer: According to Brundtland, sustainable development is development that meets the need of the present without compromising the ability of the future generations to meet their own needs.
2. What are renewable and non-renewable energy resources ? Give examples.
Answer: Renewable energy resources are generated continuously in nature and are in-exhaustible. For example – solar energy, wind energy, hydropower energy, geothermal energy, ocean thermal energy, tidal energy, wood, biomass energy, bio-fuels, hydrogen etc. They can be used again and again and are the non-conventional or alternative sources of energy.
Non-renewable energy resources are sources that have accumulated in nature, have been in use for a long time, and are exhaustible. Once these sources are finished, they cannot be replenished quickly. For example, fossil fuels (coal, petroleum, natural gas), and nuclear fuels like uranium and thorium. These are used conventionally to meet the energy demands of human society.
3. What is energy conservation ? Mention some measures for energy conservations.
Answer: Energy conservation refers to efforts made to reduce energy consumption. It can be achieved through increased efficient energy use, in conjunction with decreased energy consumption and/or reduced consumption from conventional energy sources.
The following measures for energy conservation can be adopted as initial steps:
a) Shifting from the use of fossil fuels and non renewable energy resources such as petroleum, coal, natural gas, uranium etc to renewable energy resources such as solar energy, wind energy, biogas etc.
b) More technological innovation contributing efficient energy saving.
c) Unnecessary use of electricity should be prohibited. Switch off the street lights early in the morning.
d) Domestic consumers can curtail energy consumption on many household goods.
e) Industries should develop a mechanism for judicious use of raw materials for their energy needs.
4. What is rainwater harvesting ? What are the objectives of rainwater harvesting ?
Answer: Rainwater harvesting is a technique of collection of rainwater from paved or G.I. corrugated roofs and paved courtyards of houses. It is also involved in increasing the recharge of groundwater by capturing and storing rainwater. This is done by constructing special water harvesting structures like dug wells, percolation pits, lagoons, check dams etc.
Rainwater harvesting has the following objectives:
- To reduce run off loss
- To meet increasing demands of water
- To reduce pressure on ground water resource
- To raise ground water table by the process of recharging
5. What are the advantages of rainwater harvesting ?
Answer: The advantages of rainwater harvesting are:
- It provides a source of water at the point where it is needed.
- It involves little cost and every household can easily accommodate the simple mechanism required for recycling rainwater.
- Rainwater is free from the contamination of fluoride, arsenic, iron etc.
- Recycling of rainwater for domestic and other uses can significantly reduce the pressure on ground water as ground water depletion has become a serious problem in many cities of the world.
- It provides an essential reserve in times of emergency or breakdown of public water supply systems.
- The technologies are simple and common people can easily be trained to build one storage tank of rainwater with a minimum cost.
6. How health may be affected by the environment ?
Answer: Human health is affected by the environment. Many factors like nutritional, chemical, physical, biological, psychological, and poor living conditions are correlated. More than 80% of diseases in India are water-related, including typhoid, cholera, hepatitis, polio, gastro-enteritis, amoebiasis, and giardiasis. The most common health risk from drinking water is microbial contamination. Many toxic chemicals, pesticides, and heavy metals like mercury, cadmium, and lead are released into water bodies and soil, which can enter the human body through the food chain, causing adverse impacts on health. Industries and transportation systems release gases like sulphur dioxide, carbon monoxide, and nitrous oxide, which can cause different health effects. Solid waste can degrade the air, water, and soil, posing risks to health. Improper housing with poor hygienic conditions can also cause serious health effects.
7. ‘Population explosion is the root cause of environmental degradation’- Explain the statement.
Answer: The bourgeoning population, rapid urbanization, and accelerated rates of industrialization in recent times have brought about tremendous pressure on land, water, and other natural resources. This leads to the deterioration of environmental quality, loss of life forms, and depletion of vast natural resources. The deterioration of environmental quality is inextricably linked with economic growth and development.
8. What are the major greenhouse gases ? What is greenhouse effect ?
Answer: The major greenhouse gases (GHGs) are carbon dioxide, methane, nitrous oxide, chlorofluorocarbons (CFCs), water vapour, and ozone.
The greenhouse effect is a process where energy from the sun is absorbed by the earth’s surface, which then releases it as infrared radiation. All of this rising heat is not lost to space but is partly absorbed by greenhouse gases present in the atmosphere. These gases re-emit some of the heat back to the earth’s surface. This effect is called the greenhouse effect because it is similar to the warming effect observed in a horticultural greenhouse made of glass.
9. What do you mean by global warming ? Mention a few consequences of global warming.
Answer: The rise in temperature due to the blanketing effect of an increased level of greenhouse gases is termed global warming.
A consequence of global warming is that the earth’s average temperature has increased by 0.3 – 0.6°C since the beginning of the last century. This leads to climate change, which includes unexpected changes such as rising temperatures, changes in rainfall patterns, increased droughts, and extreme colds.
10. What is acid rain ?
Answer: Oxides of sulphur and nitrogen originating from industrial operations and fossil fuel burning are the major sources of acid-forming gases in the atmosphere. When sulphur dioxide and nitrogen oxides are transported by prevailing winds, they come in contact with water vapour and form sulphuric acid and nitric acid respectively, droplets of sulphuric acid, and small particulates of sulphates and nitrates. These chemical substances come down to the earth’s surface in two forms – wet (as acid rain, snow, fog, and cloud vapour etc.) and dry (as acidic particles). The resulting mixture is called acidic deposition or commonly called acid rain.
Extra/additional questions and answers
1. What is Agenda 21?
Answer: Agenda 21 is a detailed action plan for achieving sustainable development in the 21st century. It was one of the documents that came from the ‘Earth Summit’.
2. Name two structures used for rainwater harvesting.
Answer: Two structures used for rainwater harvesting are dug wells and percolation pits. Other structures include lagoons and check dams.
3. Name two heavy metals that can contaminate water bodies.
Answer: Two heavy metals that can contaminate water bodies and soil are mercury and lead. Cadmium is another example of such a toxic heavy metal.
4. Name three major Greenhouse Gases (GHGs).
Answer: Three major Greenhouse Gases are carbon dioxide, methane, and nitrous oxide. Others include chlorofluorocarbons (CFCs), water vapor, and ozone.
5. What would be the earth’s temperature without the greenhouse effect?
Answer: Without the greenhouse effect, most of the sun’s energy would escape back into space, leaving the Earth cold with an average temperature of about -18°C, making it unfit for life.
6. What is the difference between weather and climate?
Answer: Weather refers to the day-to-day atmospheric conditions of a place, such as temperature, rainfall, and wind. Climate, on the other hand, is the average pattern of weather in an area over a long period, typically at least 30 to 40 years.
7. What is climate change?
Answer: Climate change refers to statistically significant variations in the average state of the climate over an extended period. It is a term used to describe unexpected changes like rising temperatures, altered rainfall patterns, and an increase in droughts or extreme cold.
8. What is ozone?
Answer: Ozone is a pale blue gas that is a form of oxygen.
9. Where is the ozone layer mostly present?
Answer: The ozone layer is mostly present in the stratosphere, which is a layer of the atmosphere extending up to 50 kilometers above the Earth’s surface.
10. What are CFCs?
Answer: CFCs stand for chlorofluorocarbons. They are man-made chemicals that are nontoxic, stable, inert, and inexpensive, which led to their wide use in various products.
11. Name two uses of CFCs.
Answer: Two common uses of CFCs were as refrigerants in cooling systems and as aerosol-propellants in spray cans. They were also used in cleaning solvents and for making plastic foams.
12. What is a promising substitute for CFCs?
Answer: A promising substitute for CFCs is a group of chemicals called Hydro-chloro-fluoro carbons, or HCFCs, which have a much lower ozone-depleting power.
13. When was the Montreal Protocol signed?
Answer: The Montreal Protocol was signed on September 16, 1987.
14. When is the International Day for the Protection of the Ozone Layer observed?
Answer: The International Day for the Protection of the Ozone Layer has been observed on the 16th of September every year since 1987.
15. How are environmental deterioration and economic growth inextricably linked?
Answer: Deterioration of the environmental quality and economic growth and development are inextricably linked. This is because the bourgeoning population, rapid urbanization, and accelerated rates of industrialization, which are part of economic growth, have brought about tremendous pressure on land, water, and other natural resources. This pressure leads to the deterioration of environmental quality, loss of life forms, and the depletion of vast natural resources.
16. What does sustainable development include, according to WCED?
Answer: Sustainable development is a process of change where the exploration of resources, the direction of investment, the orientation of technological advancement, and institutional changes are made consistent with both future and present needs. It also includes social and economic development on one hand and the maintenance of the environment on the other. It is based on improving the quality of life for all.
17. What is a source of energy? What are its two main types?
Answer: A source of energy is one that can provide an adequate amount of energy in a usable form over a long period of time.
The two main types of energy sources are renewable or non-conventional energy resources, and non-renewable or conventional energy resources.
18. Differentiate between renewable and non-renewable energy resources with examples.
Answer: Renewable energy resources are those that are generated continuously in nature and are inexhaustible. They can be used again and again and are also known as non-conventional or alternative sources of energy. Examples include solar energy, wind energy, hydropower, geothermal energy, biomass energy, and hydrogen.
Non-renewable energy resources are sources that have accumulated in nature over a long time and are exhaustible. Once these sources are finished, they cannot be replenished quickly. They are used conventionally to meet energy demands. Examples include fossil fuels like coal, petroleum, and natural gas, as well as nuclear fuels like uranium and thorium.
19. Why is energy consumption considered a barometer of civilization?
Answer: Energy consumption is considered a barometer of civilization, which means it is an indicator of a nation’s level of development. This is because the energy potential of a nation has a direct correlation with its economic growth and prosperity. The stage of a country’s development is well reflected by its per capita energy consumption, so a higher rate of consumption often indicates a more developed society.
20. Explain how the greenhouse effect makes the earth hospitable for life.
Answer: The greenhouse effect makes the earth hospitable for life by maintaining an average surface temperature of about 15°C. While some of the sun’s energy is reflected back into space, the rest warms the earth. The earth releases this energy as heat, but not all of it escapes. Greenhouse gases in the atmosphere absorb some of this rising heat and re-emit it back to the earth’s surface. This natural trapping of heat keeps the planet warm enough for us and other species to exist; without it, the earth would be a cold and unfit place for life.
21. How have man-made activities contributed to the increase of greenhouse gases?
Answer: Man-made, or anthropogenic, activities have contributed to the increase of greenhouse gases, particularly since the industrial revolution began 150 years ago. These activities have added significant quantities of greenhouse gases to the atmosphere. For instance, between 1750 and 2000, the atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have grown by about 31%, 171%, and 17% respectively, leading to an overall increase in the concentration of these gases.
22. Why is the ozone layer crucial for life on Earth?
Answer: The ozone layer is crucial for life on Earth because it acts as a protective shield in the biospheric ecosystem. It strongly absorbs a large portion of the sun’s deadly and dangerous ultraviolet (UV) radiation, protecting living organisms from its harmful effects. In the absence of this layer, all the UV rays would reach the Earth’s surface, causing the temperature to rise to a point where the survival of living organisms would become impossible.
23. What were the findings of scientists regarding the ozone layer in the 1980s?
Answer: In the early 1980s, scientists reported a large hole in the ozone layer over Antarctica, where the ozone level had dropped by 30%. Subsequently, a similar hole was discovered over the thickly populated northern hemisphere. Another study revealed that the amount of ozone over the northern hemisphere had decreased by 3% between 1969 and 1986, creating great concern among citizens of North Europe and the USA.
24. How do CFCs cause the destruction of the ozone layer?
Answer: Chlorofluorocarbons (CFCs) cause the destruction of the ozone layer because they are chemically inert and can remain in the atmosphere for more than 50 years. After being released, they slowly percolate into the stratosphere. There, they break down and produce free chlorine atoms. These chlorine atoms are involved in the destruction of ozone molecules. Each CFC molecule acts in a catalytic fashion, meaning it can destroy about 100,000 molecules of ozone before it is removed from the system.
25. What protective measures can be taken to prevent ozone depletion?
Answer: To prevent ozone depletion, persistent efforts should be made to find better alternatives to CFCs, such as Hydro-chloro-fluoro carbons (HCFCs) or using helium as a coolant in refrigerators. The foremost task is to markedly reduce the production and consumption of ozone-destroying CFCs. Scientists need to find suitable alternatives, and it is also important to create awareness among people regarding the dangerous effects of ozone depletion.
26. What did the Montreal Protocol call for?
Answer: The Montreal Protocol, an international agreement made in 1987, called for a freeze on the use of CFCs. It also called for a reduction of up to 50% in the use of CFCs by the end of the year 2000. This agreement was initially signed by 34 countries to protect the ozone layer.
27. How is acid rain formed in the atmosphere?
Answer: Acid rain is formed when oxides of sulphur and nitrogen are released into the atmosphere from industrial operations and the burning of fossil fuels. These gases are transported by winds and come into contact with water vapour in the atmosphere. This reaction forms sulphuric acid and nitric acid. These chemical substances then come down to the earth’s surface as wet deposition, such as acid rain, snow, or fog, or as dry deposition in the form of acidic particles.
28. What is energy conservation? Discuss the various measures that can be adopted for it.
Answer: Energy conservation refers to the efforts made to reduce the consumption of energy. It can be achieved through increased efficiency in energy use, a decrease in overall energy consumption, and a reduction in the use of conventional energy sources. Conserving energy can lead to increased financial capital, better environmental quality, and greater national and personal security. It supports an eco-friendly lifestyle by saving money while also protecting the earth, as decreasing energy use helps reduce global warming.
Several measures can be adopted for energy conservation. These initial steps include:
- Shifting from the use of non-renewable energy resources like petroleum, coal, and natural gas to renewable resources such as solar energy, wind energy, and biogas.
- Promoting more technological innovation that contributes to efficient energy saving.
- Prohibiting the unnecessary use of electricity, for example, by switching off street lights early in the morning.
- Encouraging domestic consumers to curtail energy consumption on various household goods.
- Requiring industries to develop mechanisms for the judicious use of raw materials for their energy needs.
29. What is rainwater harvesting? Explain its objectives and advantages in detail.
Answer: Rainwater harvesting is a technique for collecting rainwater from surfaces like paved or corrugated roofs and paved courtyards. It also involves increasing the recharge of groundwater by capturing and storing this rainwater. This is accomplished by constructing special structures such as dug wells, percolation pits, lagoons, and check dams. This practice is becoming increasingly common for meeting domestic water needs in both rural and urban areas, especially during dry periods.
The main objectives of rainwater harvesting are to reduce the loss of water from runoff, meet the increasing demands for water, reduce the pressure on groundwater resources, and raise the groundwater table through the process of recharging.
Rainwater harvesting offers several advantages. It provides a source of water at the exact point where it is needed. The method involves little cost, and households can easily accommodate the simple mechanism. The collected rainwater is free from contaminants like fluoride, arsenic, and iron. By recycling rainwater, the pressure on groundwater is significantly reduced, which is a serious issue in many cities. It also provides an essential water reserve in times of emergency or when public water supply systems fail. The technologies are simple, and people can be easily trained to build a storage tank with minimum cost.
30. What is the greenhouse effect? How does an increase in greenhouse gases lead to global warming?
Answer: The greenhouse effect is a natural process that warms the Earth’s surface and makes life possible. When energy from the sun reaches the Earth, some of it is reflected back into space, while the rest is absorbed, warming the planet. The Earth then releases this energy as heat. Certain gases in the atmosphere, known as Greenhouse Gases (GHGs) like carbon dioxide, methane, and water vapor, absorb some of this outgoing heat and re-emit it back towards the Earth’s surface. This trapping of heat keeps the planet’s average temperature at about 15°C, which is warm enough to support life. This process is called the greenhouse effect because it is similar to the way a glass greenhouse traps heat.
Global warming occurs when the concentration of these greenhouse gases in the atmosphere increases, enhancing the natural greenhouse effect. Human activities, particularly since the industrial revolution, have added significant quantities of greenhouse gases to the atmosphere. For instance, the atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have grown substantially. This increased level of GHGs acts like a thicker blanket around the Earth, trapping more heat. The resulting rise in the Earth’s average temperature due to this blanketing effect is termed global warming.
31. Write a short note on the Brundtland Report.
Answer: The concept of sustainable development gained much importance since the publication of the Brundtland Report, Our Common Future, in 1987 under the auspices of the World Commission on Environment and Development (WCED). According to Brundtland, sustainable development is development that meets the need of the present without compromising the ability of the future generations to meet their own needs. G.H. Brundtland was the Norwegian Prime Minister as well as the Director of the World Health Organization (WHO).
32. Write a short note on the WCED’s perspective on sustainable development.
Answer: The World Commission on Environment and Development (WCED) maintains that sustainable development is a process of change in which exploration of resources, the direction of investment, the orientation of technological advancement and institutional changes are made consistent with future as well as present needs. It also includes social and economic development on one hand, and the maintenance of the environment on the other. It is based on improving the quality of life for all.
33. Write a short note on the United Nations Conference on Environment and Development (UNCED).
Answer: The concept of sustainable development got further boost and greater attention since the United Nations Conference on Environment and Development (UNCED), popularly known as the Earth Summit, held in Rio de Janeiro in June, 1992. The UNCED came up with several documents including the Rio Declaration on Environment and Development that listed 27 principles of sustainable development, the agenda 21 which is a detailed action plan for sustainable development in the 21st century, and the convention on Biological Diversity.
34. Write a short note on Renewable energy resources.
Answer: Renewable energy resources are generated continuously in nature and are inexhaustible. For example – solar energy, wind energy, hydropower energy, geothermal energy, ocean thermal energy, tidal energy, wood, biomass energy, bio-fuels, hydrogen etc. They can be used again and again. They are the non-conventional or alternative sources of energy.
35. Write a short note on Non-renewable energy resources.
Answer: Non-renewable energy sources, accumulated in nature, have been in use since a long time and are exhaustible. Once these sources are finished, they cannot be replenished quickly. For example, fossil fuels like coal, petroleum, and natural gas, and nuclear fuels like uranium and thorium. These are used conventionally to meet the energy demands of human society.
36. Write a short note on the benefits of energy conservation.
Answer: Energy conservation can result in increased financial capital, environmental quality, national security, personal security, and human comfort. Individuals and organizations that are direct consumers of energy choose to conserve energy to reduce energy costs and promote economic security. Industrial and commercial users can increase energy use efficiency to maximize profit. Energy conservation supports the ecofriendly lifestyle by providing energy, which saves money and at the same time saves the earth. When we decrease the amount of energy, we automatically make efforts to reduce increasing global warming.
37. Write a short note on the necessity and application of rainwater harvesting in India.
Answer: Rainwater harvesting is necessary in areas experiencing significant rainfall but lacking any kind of conventional centralized government supply of water scheme and in areas where good quality of water is lacking. The North eastern region of our country gets more than sufficient rainfall during monsoon but little or sometimes no rainfall during winter, so rainwater harvesting can play a significant role to meet the growing demands of water in this region. Rainwater harvesting is extensively carried out in cities like Bangalore, Chennai, Madhya Pradesh, Rajasthan, Gujarat, Mumbai, and Delhi. In the NE region, this is carried out in Mizoram, and in some parts of Meghalaya, Arunachal Pradesh and Manipur. In some hilly areas of Guwahati city, rainwater harvesting has been done at present.
38. Write a short note on Greenhouse Gases (GHGs).
Answer: Greenhouse Gases (GHGs) are gases present in the atmosphere in very small quantities that absorb rising heat from the earth. The major GHGs are carbon dioxide, methane, nitrous oxide, chlorofluorocarbons (CFCs), water vapour and ozone. These gases re-emit some of the heat to the earth’s surface, causing the greenhouse effect.
39. Write a short note on the role and importance of the ozone layer.
Answer: Ozone is a pale blue gas, mostly present in the stratosphere, which extends up to 50 km above the surface of the earth. Ozone strongly absorbs a large portion of the sun’s ultraviolet radiation and thus protects living organisms on earth from the harmful effects of UV radiations. The role of ozone is very significant because it acts as a protective shield in the biospheric ecosystem against exposure to deadly and dangerous ultraviolet radiation.
40. Write a short note on Chlorofluorocarbons (CFCs).
Answer: Chlorofluorocarbons (CFCs) are a major group of man-made pollutants that cause ozone layer depletion. Invented in the 1930s, CFCs are nontoxic, stable, inert, inexpensive, efficient and easy to handle. They are widely used as aerosol-propellants, refrigerants, cleaning solvents, in plastic foams, fast food packaging, dry cleaning, and for sterilizing surgical instruments. Being chemically inert, they can remain in the atmosphere for more than 50 years. The CFCs are slowly released into the atmosphere and percolate into the stratosphere, where they produce free chlorine atoms. These chlorine atoms are involved in the destruction of ozone. Each CFC molecule acts in a catalytic fashion to destroy about 100,000 molecules of ozone.
41. Write a short note on the Montreal Protocol.
Answer: The Montreal Protocol is an international agreement made in 1987 at a conference in Montreal. It was initially signed by 34 countries and called for a freeze on the use of CFCs and a reduction of up to 50% by the end of 2000. The Montreal Protocol was signed on September 16, 1987, by more than 100 countries pledging to protect the ozone layer.
42. Write a short note on the formation of acid rain.
Answer: Oxides of sulphur and nitrogen originating from industrial operations and fossil fuel burning are the major sources of acid-forming gases in the atmosphere. When sulphur dioxide and nitrogen oxides are transported by prevailing winds, they come in contact with water vapour and form sulphuric acid and nitric acid respectively, droplets of sulphuric acid and small particulates of sulphates and nitrates.
43. Distinguish between Renewable and Non-renewable energy resources.
Answer: Renewable energy resources: These energy resources are generated continuously in nature and are in-exhaustible. For example – solar energy, wind energy, hydropower energy, geothermal energy, ocean thermal energy, tidal energy, wood, biomass energy, bio-fuels, hydrogen etc. They can be used again and again. They are the non-conventional or alternative sources of energy.
Non-renewable energy resources: These energy sources, accumulated in nature, have been in use since a long time and are exhaustible. Once these sources are finished, they can not be replenished quickly. For example fossil fuels (coal, petroleum, natural gas), nuclear fuels like uranium, thorium etc. These are used conventionally to meet the energy demands of human society.
44. Distinguish between conventional and non-conventional energy resources.
Answer: Conventional energy resources: These are non-renewable energy sources that have been in use for a long time. These include fossil fuels like coal, petroleum, and natural gas, as well as nuclear fuels like uranium and thorium. They are used conventionally to meet the energy demands of human society.
Non-conventional energy resources: These are renewable energy resources. These are also known as alternative sources of energy. Examples include solar energy, wind energy, hydropower energy, geothermal energy, ocean thermal energy, tidal energy, wood, biomass energy, bio-fuels, and hydrogen.
45. Distinguish between the Greenhouse effect and Global warming.
Answer: Greenhouse effect: This is a natural process where some gases present in the atmosphere, called Greenhouse Gases (GHGs), absorb part of the heat rising from the earth’s surface. These gases, which include carbon dioxide, methane, nitrous oxide, chlorofluorocarbons (CFCs), water vapour, and ozone, re-emit some of the heat back to the earth’s surface. This effect keeps the planet warm enough to allow us and other species to exist, maintaining an average surface temperature of about 15°C, which makes the earth hospitable for a variety of life forms.
Global warming: This is the rise in temperature due to the blanketing effect of an increased level of greenhouse gases. Due to different natural as well as anthropogenic activities, the concentration of greenhouse gases in the atmosphere has increased. This has caused the earth’s average temperature to increase by 0.3 – 0.6°C since the beginning of the last century.
46. Distinguish between Weather and Climate.
Answer: Weather: This means the day-to-day atmospheric condition of an area, which includes factors such as temperature, rainfall, humidity, wind, intensity of light, cloud etc.
Climate: This is the average pattern of weather of an area. It is determined by averaging weather conditions over a long period of time, at least over 30 to 40 years.
47. Distinguish between Global warming and Climate change.
Answer: Global warming: This is the rise in temperature due to the blanketing effect of an increased level of greenhouse gases in the atmosphere.
Climate change: This is a broader term that refers to statistically significant variations in the mean state of climate or in its variability over an extended period. It is used to express unexpected changes in climate, which include not only rising temperature but also changes in rainfall patterns, increased droughts, and extreme colds.
Extra/additional Fill in the Blanks
1. The concept of sustainable development gained much importance since the publication of the Brundtland Report, Our Common Future, in ______
Answer: 1987
2. The Brundtland Report was published under the auspices of the World Commission on ______ and Development (WCED).
Answer: Environment
3. According to Brundtland, sustainable development is “development that meets the need of the present without compromising the ability of the ______ generations to meet their own needs”.
Answer: future
4. G.H. Brundtland was the ______ Prime Minister.
Answer: Norwegian
5. The United Nations Conference on Environment and Development (UNCED), is popularly known as the ‘______ Summit”.
Answer: Earth
6. The ‘Earth Summit” was held in Rio de Janeiro in June, ______.
Answer: 1992
7. The Rio Declaration on Environment and Development listed ______ principles of sustainable development.
Answer: 27
8. ______ is a detailed action plan for sustainable development in the 21st century.
Answer: Agenda 21
9. The capacity to do work is called ______.
Answer: energy
10. Solar energy, wind energy, and hydropower energy are examples of ______ energy resources.
Answer: Renewable
11. Fossil fuels like coal and petroleum are examples of ______ energy resources.
Answer: Non-renewable
12. ______ refers to efforts made to reduce energy consumption.
Answer: Energy conservation
13. ______ is a technique of collection of rainwater from paved or G.I. corrugated roofs and paved courtyard of houses.
Answer: Rainwater harvesting
14. According to the World Health Organization (WHO), health is “a state of complete physical, mental and ______ well being”.
Answer: social
15. More than ______% of diseases in India are water-related.
Answer: 80
16. The earth has an atmosphere of proper thickness and ______ composition.
Answer: chemical
17. About ______% of the incoming energy from the sun is reflected back to space.
Answer: 30
18. The average surface temperature of the earth is about ______°C.
Answer: 15
19. The major Greenhouse Gases (GHGs) include carbondioxide, methane, and ______ oxide.
Answer: nitrous
20. If GHGs did not perform their function, the earth would be cold at about ______°C.
Answer: -18
21. The rise in temperature due to the blanketing effect of increased level of greenhouse gases is termed as ______.
Answer: global warming
22. ______ is a pale blue gas, mostly present in the stratosphere.
Answer: Ozone
23. The maximum ozone concentration is around 10 ppm in the ______ at an altitude of 25-30 km.
Answer: stratosphere
24. In the early 80’s scientists reported a large hole in the ozone layer over ______.
Answer: Antarctica
25. The main cause of ozone layer depletion is the stratospheric concentration of man-made pollutants like ______.
Answer: chlorofluorocarbons (CFCs)
26. Each CFC molecule acts in a catalytic fashion to destroy about ______ molecules of ozone.
Answer: 100,000
27. An international agreement made in 1987 at a conference in Montreal is known as the ______.
Answer: Montreal Protocol
28. ______ has been observed as the International day for the protection of the Ozone layer since 1987.
Answer: 16th September
29. Oxides of sulphur and ______ are the major sources of acid-forming gases in the atmosphere.
Answer: nitrogen
