Case Study Questions Class 11 Chemistry Chapter 14 Environmental chemistry
CBSE Class 11 Case Study Questions Chemistry Environmental chemistry. Important Case Study Questions for Class 11 Board Exam Students. Here we have arranged some Important Case Base Questions for students who are searching for Paragraph Based Questions Environmental chemistry.
At Case Study Questions there will given a Paragraph. In where some Important Questions will made on that respective Case Based Study. There will various types of marks will given 1 marks, 2 marks, 3 marks, 4 marks.
CBSE Case Study Questions Class 11 Chemistry Environmental chemistry
Case Study – 1
Environmental chemistry deals with the study of the origin, transport, reactions, effects and fates of chemical species in the environment. Environmental pollution is the effect of undesirable changes in our surroundings that have harmful effects on plants, animals and human beings. A substance, which causes pollution, is known as pollutant. Pollutants can be solid, liquid or gaseous substances present in greater concentration than in natural abundance and are produced due to human activities or due to natural happenings. The atmosphere that surrounds the earth is not of the same thickness at all heights. There are concentric layers of air or regions and each layer has different density. The lowest region of atmosphere in which the human beings along with other organisms live is called troposphere. It extends up to the height of ~ 10 km from sea level. Above the troposphere, between 10 and 50 km above sea level lies stratosphere. Troposphere is a turbulent, dusty zone containing air, much water vapour and clouds. This is the region of strong air movement and cloud formation. The stratosphere, on the other hand, contains dinitrogen, dioxygen, ozone and little water vapour. Atmospheric pollution is generally studied as tropospheric and stratospheric pollution. The presence of ozone in the stratosphere prevents about 99.5 per cent of the sun’s harmful ultraviolet (UV) radiations from reaching the earth’s surface and thereby protecting humans and other animals from its effect. Tropospheric pollution occurs due to the presence of undesirable solid or gaseous particles in the air. The following are the major gaseous and particulate pollutants present in the troposphere:
1) Gaseous air pollutants: These are oxides of sulphur, nitrogen and carbon, hydrogen sulphide, hydrocarbons, ozone and other oxidants.
2) Particulate pollutants: These are dust, mist, fumes, smoke, smog etc.
Gaseous air pollutants-
(a) Oxides of Sulphur: Oxides of sulphur are produced when sulphur containing fossil fuel is burnt. The most common species, sulphur dioxide, is a gas that is poisonous to both animals and plants. It has been reported that even a low concentration of sulphur dioxide causes respiratory diseases e.g., asthma, bronchitis, emphysema in human beings. Sulphur dioxide causes irritation to the eyes, resulting in tears and redness. High concentration of SO2 leads to stiffness of flower buds which eventually fall off from plants. Uncatalysed oxidation of sulphur dioxide is slow.
(b) Oxides of Nitrogen: Dinitrogen and dioxygen are the main constituents of air. These gases do not react with each other at a normal temperature. At high altitudes when lightning strikes, they combine to form oxides of nitrogen. NO2 is oxidised to nitrate ion, NO3− which is washed into soil, where it serves as a fertilizer. It is toxic to living tissues also. Nitrogen dioxide is also harmful to various textile fibres and metals.
(c) Hydrocarbons: Hydrocarbons are composed of hydrogen and carbon only and are formed by incomplete combustion of fuel used in automobiles. Hydrocarbons are carcinogenic, i.e., they cause cancer. They harm plants by causing ageing, breakdown of tissues and shedding of leaves, flowers and twigs.
(d) Oxides of Carbon
(i) Carbon monoxide: Carbon monoxide (CO) is one of the most serious air pollutants. It is a colourless and odourless gas, highly poisonous to living beings because of its ability to block the delivery of oxygen to the organs and tissues. It is produced as a result of incomplete combustion of carbon. Carbon monoxide is mainly released into the air by automobile exhaust. Other sources, which produce CO, involve incomplete combustion of coal, firewood, petrol, etc. The number of vehicles has been increasing over the years all over the world. Many vehicles are poorly maintained and several have inadequate pollution control equipments resulting in the release of greater amount of carbon monoxide and other polluting gases.
(ii) Carbon dioxide: Carbon dioxide (CO2) is released into the atmosphere by respiration, burning of fossil fuels for energy, and by decomposition of limestone during the manufacture of cement. It is also emitted during volcanic eruptions. Carbon dioxide gas is confined to troposphere only. Normally it forms about 0.03 per cent by volume of the atmosphere. With the increased use of fossil fuels, a large amount of carbon dioxide gets released into the atmosphere. Global Warming and Greenhouse Effect
About 75 % of the solar energy reaching the earth is absorbed by the earth’s surface, which increases its temperature. The rest of the heat radiates back to the atmosphere. Some of the heat is trapped by gases such as carbon dioxide, methane, ozone, chlorofluorocarbon compounds (CFCs) and water vapour in the atmosphere. Thus, they add to the heating of the atmosphere. This causes global warming. we are not surrounded by glass but a blanket of air called the atmosphere, which has kept the temperature on earth constant for centuries. But it is now undergoing change, though slowly. Just as the glass in a greenhouse holds the sun’s warmth inside, atmosphere traps the sun’s heat near the earth’s surface and keeps it warm. This is called natural greenhouse effect because it maintains the temperature and makes the earth perfect for life.
[A] MCQ
1) The lowest region of atmosphere in which the human beings along with other organisms live is called…
a) troposphere
b) stratosphere
c) mesosphere
d) thermosphere
Ans- a) troposphere
2) Above the troposphere, between 10 and 50 km above sea level lies …
a) exosphere
b) stratosphere
c) mesosphere
d) thermosphere
Ans- b) stratosphere
3) Ozon presents in … region .
a) exosphere
b) mesosphere
c) stratosphere
d) thermosphere
Ans- c) stratosphere
4) … is released into the atmosphere by respiration.
a) Oxygen
b) Hydrogen
c) Nitrogen
d) Carbon dioxide
Ans- d) Carbon dioxide
5) stratosphere lies between … km above sea level .
a) 0-10
b) 10-50
c) 50-100
d) 100-150
Ans- b) 10-50
[B]Short Answers
1) What is Atmospheric pollution ?
Ans- Atmospheric pollution is generally studied as tropospheric and stratospheric pollution. The presence of ozone in the stratosphere prevents about 99.5 per cent of the sun’s harmful ultraviolet (UV) radiations from reaching the earth’s surface and thereby protecting humans and other animals from its effect. Tropospheric pollution occurs due to the presence of undesirable solid or gaseous particles in the air.
2) What is pollutant ?
Ans- Environmental pollution is the effect of undesirable changes in our surroundings that have harmful effects on plants, animals and human beings. A substance, which causes pollution, is known as pollutant. Pollutants can be solid, liquid or gaseous substances present in greater concentration than in natural abundance and are produced due to human activities or due to natural happenings.
3) Describe 1) tropospheric 2) stratosphere .
Ans- The atmosphere that surrounds the earth is not of the same thickness at all heights. There are concentric layers of air or regions and each layer has different density. The lowest region of atmosphere in which the human beings along with other organisms live is called troposphere. It extends up to the height of ~ 10 km from sea level. Above the troposphere, between 10 and 50 km above sea level lies stratosphere.
[C]Long Answers
1) Explains Oxides of carbon .
Ans- Oxides of Carbon are as follows –
(i) Carbon monoxide: Carbon monoxide (CO) is one of the most serious air pollutants. It is a colourless and odourless gas, highly poisonous to living beings because of its ability to block the delivery of oxygen to the organs and tissues. It is produced as a result of incomplete combustion of carbon. Carbon monoxide is mainly released into the air by automobile exhaust. Other sources, which produce CO, involve incomplete combustion of coal, firewood, petrol, etc. The number of vehicles has been increasing over the years all over the world. Many vehicles are poorly maintained and several have inadequate pollution control equipments resulting in the release of greater amount of carbon monoxide and other polluting gases.
(ii) Carbon dioxide: Carbon dioxide (CO2) is released into the atmosphere by respiration, burning of fossil fuels for energy, and by decomposition of limestone during the manufacture of cement. It is also emitted during volcanic eruptions. Carbon dioxide gas is confined to troposphere only. Normally it forms about 0.03 per cent by volume of the atmosphere. With the increased use of fossil fuels, a large amount of carbon dioxide gets released into the atmosphere. Global Warming and Greenhouse Effect
2) What is Global warming ? What is Greenhouse effect ?
Ans- About 75 % of the solar energy reaching the earth is absorbed by the earth’s surface, which increases its temperature. The rest of the heat radiates back to the atmosphere. Some of the heat is trapped by gases such as carbon dioxide, methane, ozone, chlorofluorocarbon compounds (CFCs) and water vapour in the atmosphere. Thus, they add to the heating of the atmosphere. This causes global warming. We are not surrounded by glass but a blanket of air called the atmosphere, which has kept the temperature on earth constant for centuries. But it is now undergoing change, though slowly. Just as the glass in a greenhouse holds the sun’s warmth inside, atmosphere traps the sun’s heat near the earth’s surface and keeps it warm. This is called natural greenhouse effect because it maintains the temperature and makes the earth perfect for life.
Case Study – 2
We are aware that normally rain water has a pH of 5.6 due to the presence of H+ ions formed by the reaction of rain water with carbon dioxide present in the atmosphere. When the pH of the rain water drops below 5.6, it is called acid rain. the atmosphere is deposited on the earth’s surface. Oxides of nitrogen and sulphur which are acidic in nature can be blown by wind along with solid particles in the atmosphere and finally settle down either on the ground as dry deposition or in water, fog and snow as wet deposition.
Acid rain is a byproduct of a variety of human activities that emit the oxides of sulphur and nitrogen in the atmosphere. As mentioned earlier, burning of fossil fuels (which contain sulphur and nitrogenous matter) such as coal and oil in power stations and furnaces or petrol and diesel in motor engines produce sulphur dioxide and nitrogen oxides. SO2 and NO2 after oxidation and reaction with water are major contributors to acid rain, because polluted air usually contains particulate matter that catalyse the oxidation.
Particulates pollutants are the minute solid particles or liquid droplets in air. These are present in vehicle emissions, smoke particles from fires, dust particles and ash from industries. Particulates in the atmosphere may be viable or non-viable. The viable particulates e.g., bacteria, fungi, moulds, algae etc., are minute living organisms that are dispersed in the atmosphere. Human beings are allergic to some of the fungi found in air. They can also cause plant diseases. Non-viable particulates may be classified according to their nature and size as follows:
(a) Smoke particulates consist of solid or mixture of solid and liquid particles formed during combustion of organic matter. Examples are cigarette smoke, smoke from burning of fossil fuel, garbage and dry leaves, oil smoke etc.
(b) Dust is composed of fine solid particles (over 1µm in diameter), produced during crushing, grinding and attribution of solid materials. Sand from sand blasting, saw dust from wood works, pulverized coal, cement and fly ash from factories, dust storms etc., are some typical examples of this type of particulate emission.
(c) Mists are produced by particles of spray liquids and by condensation of vapours in air. Examples are sulphuric acid mist and herbicides and insecticides that miss their targets and travel through air and form mists.
(d) Fumes are generally obtained by the condensation of vapours during sublimation, distillation, boiling and several other chemical reactions. Generally, organic solvents, metals and metallic oxides form fume particles.
The effect of particulate pollutants are largely dependent on the particle size. Air- borne particles such as dust, fumes, mist etc., are dangerous for human health. Particulate pollutants bigger than 5 microns are likely to lodge in the nasal passage, whereas particles of about 10 micron enter into lungs easily.
Lead used to be a major air pollutant emitted by vehicles. Leaded petrol used to be the primary source of air-borne lead emission in Indian cities. This problem has now been overcome by using unleaded petrol in most of the cities in India. Lead interferes with the development and maturation of red blood cells.
The word smog is derived from smoke and fog. This is the most common example of air pollution that occurs in many cities throughout the world. There are two types of smog:
(a) Classical smog occurs in cool humid climate. It is a mixture of smoke, fog and sulphur dioxide. Chemically it is a reducing mixture and so it is also called as reducing smog.
(b) Photochemical smog occurs in warm, dry and sunny climate. The main components of the photochemical smog result from the action of sunlight on unsaturated hydrocarbons and nitrogen oxides produced by automobiles and factories. Photochemical smog has high concentration of oxidising agents and is, therefore, called as oxidising smog.
The common components of photochemical smog are ozone, nitric oxide, acrolein, formaldehyde and peroxyacetyl nitrate (PAN). Photochemical smog causes serious health problems. Both ozone and PAN act as powerful eye irritants. Ozone and nitric oxide irritate the nose and throat and their high concentration causes headache, chest pain, dryness of the throat, cough and difficulty in breathing. Photochemical smog leads to cracking of rubber and extensive damage to plant life. It also causes corrosion of metals, stones, building materials, rubber and painted surfaces.
[A] MCQ
1) Normally rain water has a pH of …
a) 6
b) 5
c) 0
d) 5
Ans- a) 5.6
2) When the pH of the rain water drops below 5.6, it is called … rain.
a) basic
b) acid
c) neutral
d) alkaline
Ans- b) acid
3) Particulate pollutants bigger than … microns are likely to lodge in the nasal passage
a) 1
b) 3
c) 5
d) 7
Ans- c) 5
4) Particles of about … micron enter into lungs easily.
a) 20
b) 1
c) 5
d) 10
Ans- d) 10
5) … also causes corrosion of metals, stones, building materials, rubber and painted surfaces.
a) photochemical smog
b) sulfurous smog
c) Classical Smog
d) All the above
Ans- a) photochemical smog
[B]Short Answers
1) What is smog ? Give classification of smog .
Ans- The word smog is derived from smoke and fog. This is the most common example of air pollution that occurs in many cities throughout the world. There are two types of smog:
(a) Classical smog occurs in cool humid climate. It is a mixture of smoke, fog and sulphur dioxide. Chemically it is a reducing mixture and so it is also called as reducing smog.
(b) Photochemical smog occurs in warm, dry and sunny climate. The main components of the photochemical smog result from the action of sunlight on unsaturated hydrocarbons and nitrogen oxides produced by automobiles and factories. Photochemical smog has high concentration of oxidising agents and is, therefore, called as oxidising smog.
2) What are effects of photochemical smog ?
Ans- The common components of photochemical smog are ozone, nitric oxide, acrolein, formaldehyde and peroxyacetyl nitrate (PAN). Photochemical smog causes serious health problems. Both ozone and PAN act as powerful eye irritants. Ozone and nitric oxide irritate the nose and throat and their high concentration causes headache, chest pain, dryness of the throat, cough and difficulty in breathing. Photochemical smog leads to cracking of rubber and extensive damage to plant life. It also causes corrosion of metals, stones, building materials, rubber and painted surfaces.
3) What are the effect of particulate pollutants ?
Ans- The effect of particulate pollutants are largely dependent on the particle size. Air- borne particles such as dust, fumes, mist etc., are dangerous for human health. Particulate pollutants bigger than 5 microns are likely to lodge in the nasal passage, whereas particles of about 10 micron enter into lungs easily. Lead used to be a major air pollutant emitted by vehicles. Leaded petrol used to be the primary source of air-borne lead emission in Indian cities. This problem has now been overcome by using unleaded petrol in most of the cities in India. Lead interferes with the development and maturation of red blood cells.
[C]Long Answers
1) Explain the term particulate pollutant ?
Ans- Particulates pollutants are the minute solid particles or liquid droplets in air. These are present in vehicle emissions, smoke particles from fires, dust particles and ash from industries. Particulates in the atmosphere may be viable or non-viable. The viable particulates e.g., bacteria, fungi, moulds, algae etc., are minute living organisms that are dispersed in the atmosphere. Human beings are allergic to some of the fungi found in air. They can also cause plant diseases. Non-viable particulates may be classified according to their nature and size as follows:
a) Smoke particulates consist of solid or mixture of solid and liquid particles formed during combustion of organic matter. Examples are cigarette smoke, smoke from burning of fossil fuel, garbage and dry leaves, oil smoke etc.
b) Dust is composed of fine solid particles (over 1µm in diameter), produced during crushing, grinding and attribution of solid materials. Sand from sand blasting, saw dust from wood works, pulverized coal, cement and fly ash from factories, dust storms etc., are some typical examples of this type of particulate emission.
c) Mists are produced by particles of spray liquids and by condensation of vapours in air. Examples are sulphuric acid mist and herbicides and insecticides that miss their targets and travel through air and form mists.
d) Fumes are generally obtained by the condensation of vapours during sublimation, distillation, boiling and several other chemical reactions. Generally, organic solvents, metals and metallic oxides form fume particles.
2) What is acid rain ?
Ans- Normally rain water has a pH of 5.6 due to the presence of H+ ions formed by the reaction of rain water with carbon dioxide present in the atmosphere. When the pH of the rain water drops below 5.6, it is called acid rain. the atmosphere is deposited on the earth’s surface. Oxides of nitrogen and sulphur which are acidic in nature can be blown by wind along with solid particles in the atmosphere and finally settle down either on the ground as dry deposition or in water, fog and snow as wet deposition. Acid rain is a byproduct of a variety of human activities that emit the oxides of sulphur and nitrogen in the atmosphere. As mentioned earlier, burning of fossil fuels such as coal and oil in power stations and furnaces or petrol and diesel in motor engines produce sulphur dioxide and nitrogen oxides. SO2 and NO2 after oxidation and reaction with water are major contributors to acid rain, because polluted air usually contains particulate matter that catalyse the oxidation.
Case Study – 3
The upper stratosphere consists of Considerable amount of ozone (O3), which Protects us from the harmful ultraviolet (UV) Radiations (λ 255 nm) coming from the sun. These radiations cause skin cancer (melanoma) in humans. Therefore, it is Important to maintain the ozone shield. Ozone in the stratosphere is a product of UV radiations acting on dioxygen (O2) Molecules. The UV radiations split apart Molecular oxygen into free oxygen (O) atoms. These oxygen atoms combine with the Molecular oxygen to form ozone.
In 1980s atmospheric scientists working in Antarctica reported about depletion of ozone Layer commonly known as ozone hole over the South Pole. It was found that a unique set of Conditions was responsible for the ozone hole. In summer season, nitrogen dioxide and Methane react with chlorine monoxide (reaction iv) and chlorine atoms (reaction v) Forming chlorine sinks, preventing much ozone Depletion, whereas in winter, special type of Clouds called polar stratospheric clouds are Formed over Antarctica. These polar Stratospheric clouds provide surface on which Chlorine nitrate formed (reaction iv) gets Hydrolysed to form hypochlorous acid (reaction (vi)). It also reacts with hydrogen Chloride produced as per reaction (v) to give Molecular chlorine.
When sunlight returns to the Antarctica in The spring, the sun’s warmth breaks up the Clouds and HOCl and Cl2 are photolysed by Sunlight, as given in reactions.
The chlorine radicals thus formed, initiate The chain reaction for ozone depletion as Described earlier.
With the depletion of ozone layer, more UV Radiation filters into troposphere. UV Radiations lead to ageing of skin, cataract, Sunburn, skin cancer, killing of many Phytoplanktons, damage to fish productivity Etc. It has also been reported that plant Proteins get easily affected by UV radiations Which leads to the harmful mutation of cells. It also increases evaporation of surface water Through the stomata of the leaves and Decreases the moisture content of the soil. Increase in UV radiations damage paints and Fibres, causing them to fade faster.
Water is essential for life. Without water there Would be no life. We usually take water as Granted for its purity, but we must ensure the Quality of water. Pollution of water originates From human activities. Through different Paths, pollution reaches surface or ground Water. Easily identified source or place of Pollution is called as point source. E.g., Municipal and industrial discharge pipes Where pollutants enter the water-source. Non Point sources of pollution are those where a Source of pollution cannot be easily identified, e.g., agricultural run off (from farm, animals and crop-lands), acid rain, storm-water drainage (from streets, parking lots and lawns), etc.
Causes of Water Pollution are as follows –
1) Pathogens – The most serious water Pollutants are the disease causing agents Called pathogens. Pathogens include bacteria And other organisms that enter water from Domestic sewage and animal excreta. Human Excreta contain bacteria such as Escherichia Coli and Streptococcus faecalis which cause Gastrointestinal diseases.
2) Organic wastes: The other major water Pollutant is organic matter such as Leaves, grass, trash etc. They pollute water as consequence of run off. Excessive Phytoplankton growth within water is also a Cause of water pollution. These wastes are Biodegradable. The large population of bacteria Decomposes organic matter present in water. They consume oxygen dissolved in water. The Amount of oxygen that water can hold in the Solution is limited. In cold water, dissolved Oxygen (DO) can reach a concentration up to 10 ppm (parts per million), whereas oxygen in Air is about 200,000 ppm . the amount of oxygen required by Bacteria to break down the organic matter Present in a certain volume of a sample of Water, is called Biochemical Oxygen Demand (BOD) .
3) Chemical Pollutants: As we know that Water is an excellent solvent, water soluble Inorganic chemicals that include heavy metals Such as cadmium, mercury, nickel etc Constitute an important class of pollutants. All These metals are dangerous to humans Because our body cannot excrete them. Over The time, it crosses the tolerance limit. These Metals then can damage kidneys, central Nervous system, liver etc. Acids (like sulphuric Acid) from mine drainage and salts from many Different sources including raw salt used to Melt snow and ice in the colder climates (sodium and calcium chloride) are water Soluble chemical pollutants. Process in which nutrient Enriched water bodies support a dense plant Population, which kills animal life by depriving It of oxygen and results in subsequent loss of Biodiversity is known as Eutrophication.
[A] MCQ
1) The process in which nutrient enriched water bodies support a dense plant population, which kills animal life by depriving it of oxygen and results in subsequent loss of biodiversity is known as …
a) Eutrophication
b) Biomagnification
c) Oligotrophication
d) None of above
Ans- a) Eutrophication
2) The concentration of dissolved oxygen of water is below … ppm, the growth of
fish gets inhibited.
a) 60
b) 6
c) 600
d) 6000
Ans- b) 6
3) The harmful ultraviolet (UV) having radiations …
a) λ 55 nm
b) λ 155 nm
c) λ 255 nm
d) λ 355 nm
Ans- c) λ 255 nm
4) Clean water would have BOD value of less than …
a) 15 ppm
b) 50 ppm
c) 500 ppm
d) 5 ppm
Ans- d) 5 ppm
5) Highly polluted water could have a BOD value of …
a) 1.7 ppm or more.
b) 1700 ppm or more.
c) 17 ppm or more.
d) 170 ppm or more.
Ans- c) 17 ppm or more.
[B]Short Answers
1) What are the effects of Depletion of the Ozone Layer ?
Ans- With the depletion of ozone layer, more UV Radiation filters into troposphere. UV Radiations lead to ageing of skin, cataract, Sunburn, skin cancer, killing of many Phytoplanktons, damage to fish productivity Etc. It has also been reported that plant Proteins get easily affected by UV radiations Which leads to the harmful mutation of cells. It also increases evaporation of surface water Through the stomata of the leaves and Decreases the moisture content of the soil. Increase in UV radiations damage paints and Fibres, causing them to fade faster.
2) Write short note on water pollution .
Ans- Water is essential for life. Without water there Would be no life. We usually take water as Granted for its purity, but we must ensure the Quality of water. Pollution of water originates From human activities. Through different Paths, pollution reaches surface or ground Water. Easily identified source or place of Pollution is called as point source. E.g., Municipal and industrial discharge pipes Where pollutants enter the water-source. Non Point sources of pollution are those where a Source of pollution cannot be easily identified, e.g., agricultural run off (from farm, animals and crop-lands), acid rain, storm-water drainage (from streets, parking lots and lawns), etc.
3) Explain the formation of ozon .
Ans- The upper stratosphere consists of Considerable amount of ozone (O3), which Protects us from the harmful ultraviolet (UV) Radiations (λ 255 nm) coming from the sun. These radiations cause skin cancer (melanoma) in humans. Therefore, it is Important to maintain the ozone shield. Ozone in the stratosphere is a product of UV radiations acting on dioxygen (O2) Molecules. The UV radiations split apart Molecular oxygen into free oxygen (O) atoms. These oxygen atoms combine with the Molecular oxygen to form ozone.
[C]Long Answers
1) Write short note on ozon hole .
Ans- In 1980s atmospheric scientists working in Antarctica reported about depletion of ozone Layer commonly known as ozone hole over the South Pole. It was found that a unique set of Conditions was responsible for the ozone hole. In summer season, nitrogen dioxide and Methane react with chlorine monoxide (reaction iv) and chlorine atoms (reaction v) Forming chlorine sinks, preventing much ozone Depletion, whereas in winter, special type of Clouds called polar stratospheric clouds are Formed over Antarctica. These polar Stratospheric clouds provide surface on which Chlorine nitrate formed (reaction iv) gets Hydrolysed to form hypochlorous acid (reaction (vi)). It also reacts with hydrogen Chloride produced as per reaction (v) to give Molecular chlorine.
When sunlight returns to the Antarctica in The spring, the sun’s warmth breaks up the Clouds and HOCl and Cl2 are photolysed by Sunlight, as given in reactions.
The chlorine radicals thus formed, initiate The chain reaction for ozone depletion.
2) What are the causes of water pollution ?
Ans- 1) Pathogens – The most serious water Pollutants are the disease causing agents Called pathogens. Pathogens include bacteria And other organisms that enter water from Domestic sewage and animal excreta. Human Excreta contain bacteria such as Escherichia Coli and Streptococcus faecalis which cause Gastrointestinal diseases.
2) Organic wastes: The other major water Pollutant is organic matter such as Leaves, grass, trash etc. They pollute water as consequence of run off. Excessive Phytoplankton growth within water is also a Cause of water pollution. These wastes are Biodegradable. The large population of bacteria Decomposes organic matter present in water. They consume oxygen dissolved in water. The Amount of oxygen that water can hold in the Solution is limited. In cold water, dissolved Oxygen (DO) can reach a concentration up to 10 ppm (parts per million), whereas oxygen in Air is about 200,000 ppm . the amount of oxygen required by Bacteria to break down the organic matter Present in a certain volume of a sample of Water, is called Biochemical Oxygen Demand (BOD) .
3) Chemical Pollutants: As we know that water is an excellent solvent, water soluble Inorganic chemicals that include heavy metals Such as cadmium, mercury, nickel etc Constitute an important class of pollutants. All These metals are dangerous to humans Because our body cannot excrete them. Over The time, it crosses the tolerance limit. These Metals then can damage kidneys, central Nervous system, liver etc.
Case Study – 4
The International Standards for drinking water are given below and they must be followed.
Fluoride: For drinking purposes, water Should be tested for fluoride ion concentration. Its deficiency in drinking water is harmful to Man and causes diseases such as tooth decay Etc. Soluble fluoride is often added to drinking Water to bring its concentration upto 1 ppm Or 1 mg dm–3. The F– Ions make the enamel on Teeth much harder by converting Hydroxyapatite, [3(Ca3(PO4)2.Ca(OH)2], the Enamel on the surface of the teeth, into much Harder fluorapatite, [3(Ca3(PO4)2.CaF2]. However, F– Ion concentration above 2 ppm Causes brown mottling of teeth. At the same Time, excess fluoride (over 10 ppm) causes Harmful effect to bones and teeth, as reported From some parts of Rajasthan.
Lead: Drinking water gets contaminated with Lead when lead pipes are used for Transportation of water. The prescribed upper Limit concentration of lead in drinking water Is about 50 ppb. Lead can damage kidney, Liver, reproductive system etc.
Sulphate: Excessive sulphate (>500 ppm) in Drinking water causes laxative effect, otherwise At moderate levels it is harmless.
Nitrate: The maximum limit of nitrate in Drinking water is 50 ppm. Excess nitrate in Drinking water can cause disease such as Methemoglobinemia (‘blue baby’ syndrome). Other metals: The maximum concentration Of some common metals recommended in Drinking water.
India being an agriculture based economy Gives high priority to agriculture, fisheries and Livestock development. The surplus Production is stored by governmental and Non-governmental organisations for the lean Season. The food loss during the storage also Needs special attention. Have you ever seen the Damages caused to the crops, food items by Insects, rodents, weeds and crop diseases etc? How can we protect them? You are acquainted With some insecticides and pesticides for Protection of our crops. However, these Insecticides, pesticides and herbicides cause Soil pollution. Hence, there is a need for their Judicious use.
Prior to World War II, many naturally Occurring chemicals such as nicotine (by Planting tobacco plants in the crop field), were Used as pest controlling substance for major Crops in agricultural practices. During World War II, DDT was found to be Of great use in the control of malaria and other Insect-borne diseases. Therefore, after the war, DDT was put to use in agriculture to control The damages caused by insects, rodents, weeds And various crop diseases. However, due to Adverse effects, its use has been banned in India. Pesticides are basically synthetic toxic Chemicals with ecological repercussions. The Repeated use of the same or similar pesticides Give rise to pests that are resistant to that group of pesticides thus making the pesticides Ineffective. Therefore, as insect resistance of DDT increased, other organic toxins such as Aldrin and Dieldrin were introduced in the Market by pesticide industry. These days, the pesticide industry has Shifted its attention to herbicides such a sodium chlorate (NaClO3), sodium arsinite (Na3AsO3) and many others. During the first Half of the last century, the shift from Mechanical to chemical weed control had Provided the industry with flourishing Economic market. But one must remember that These are also not environment friendly.
Industrial solid wastes are also sorted out as Biodegradable and non-degradable wastes. Biodegradable wastes are generated by cotton Mills, food processing units, paper mills, and Textile factories. Non-biodegradable wastes are generated By thermal power plants which produce fly Ash; integrated iron and steel plants which Produce blast furnace slag and steel melting Slag. Industries manufacturing aluminium, Zinc and copper produce mud and tailings. Fertilizer industries produce gypsum. Hazardous wastes such as inflammables, Composite explosives or highly reactive Substances are produced by industries Dealing in metals, chemicals, drugs, pharma- Ceuticals, dyes, pesticides, rubber goods etc. The disposal of non-degradable industrial Solid wastes, if not done by a proper and Suitable method, may cause serious threat to The environment. New innovations have led to Different uses of waste material. Nowadays, Fly ash and slag from the steel industry are Utilised by the cement industry. Large quantities of toxic wastes are usually destroyed By controlled incineration, whereas small Quantities are burnt along with factory Garbage in open bins. Moreover, solid wastes If not managed effectively, affect the Components of the environment .
[A] MCQ
1) Soluble fluoride is often added to drinking water to bring its concentration upto …
a) 1 mg dm–3
b) 5 mg dm–3
c) 10 mg dm–3
d) 50 mg dm–3
Ans- a) 1 mg dm–3
2) Methemoglobinemia is also known as … syndrome.
a) black baby
b) blue baby
c) red baby
d) white baby
Ans- b) blue baby
3) DDT was found to be of great use in the control of …
a) cancer
b) hepatitis
c) malaria
d) COVID-19
Ans- c) malaria
4) The prescribed upper limit concentration of lead in drinking water is about … ppb.
a) 15
b) 25
c) 35
d) 50
Ans- d) 50
5) The maximum limit of nitrate in drinking water is 50 …
a) ppb
b) ppt
c) ppm
d) ppq
Ans- c) ppm
[B]Short Answers
1) Write short note on fluoride ion concentration in water .
Ans- Fluoride: For drinking purposes, water Should be tested for fluoride ion concentration. Its deficiency in drinking water is harmful to Man and causes diseases such as tooth decay Etc. Soluble fluoride is often added to drinking Water to bring its concentration upto 1 ppm Or 1 mg dm–3. The F– Ions make the enamel on Teeth much harder by converting Hydroxyapatite, [3(Ca3(PO4)2.Ca(OH)2], the Enamel on the surface of the teeth, into much Harder fluorapatite, [3(Ca3(PO4)2.CaF2]. However, F– Ion concentration above 2 ppm Causes brown mottling of teeth. At the same Time, excess fluoride (over 10 ppm) causes Harmful effect to bones and teeth, as reported From some parts of Rajasthan.
2) Give the prescribed upper limit concentration in drinking water of
1) Lead 2) Sulphate 3) Nitrate
Ans- The International Standards upper limit concentration for drinking water are given below and they must be followed.
Lead: Drinking water gets contaminated with Lead when lead pipes are used for Transportation of water. The prescribed upper Limit concentration of lead in drinking water Is about 50 ppb. Lead can damage kidney, Liver, reproductive system etc.
Sulphate: Excessive sulphate (>500 ppm) in Drinking water causes laxative effect, otherwise At moderate levels it is harmless.
Nitrate: The maximum limit of nitrate in Drinking water is 50 ppm. Excess nitrate in Drinking water can cause disease such as Methemoglobinemia (‘blue baby’ syndrome).
3) Write the short note on soil pollution .
Ans- India being an agriculture based economy Gives high priority to agriculture, fisheries and Livestock development. The surplus Production is stored by governmental and Non-governmental organisations for the lean Season. The food loss during the storage also Needs special attention. Have you ever seen the Damages caused to the crops, food items by Insects, rodents, weeds and crop diseases etc? How can we protect them? You are acquainted With some insecticides and pesticides for Protection of our crops. However, these Insecticides, pesticides and herbicides cause Soil pollution. Hence, there is a need for their Judicious use
[C]Long Answers
1) What are pesticides ? Write short note on pesticides .
Ans- Many naturally occurring chemicals such as nicotine (by Planting tobacco plants in the crop field), were Used as pest controlling substance for major Crops in agricultural practices. During World War II, DDT was found to be Of great use in the control of malaria and other Insect-borne diseases. Therefore, after the war, DDT was put to use in agriculture to control The damages caused by insects, rodents, weeds And various crop diseases. However, due to Adverse effects, its use has been banned in India. Pesticides are basically synthetic toxic Chemicals with ecological repercussions. The Repeated use of the same or similar pesticides Give rise to pests that are resistant to that group of pesticides thus making the pesticides Ineffective. Therefore, as insect resistance of DDT increased, other organic toxins such as Aldrin and Dieldrin were introduced in the Market by pesticide industry. These days, the pesticide industry has Shifted its attention to herbicides such a sodium chlorate (NaClO3), sodium arsinite (Na3AsO3) and many others. During the first Half of the last century, the shift from Mechanical to chemical weed control had Provided the industry with flourishing Economic market. But one must remember that These are also not environment friendly.
2) Explain the term industrial waste.
Ans- Industrial solid wastes are also sorted out as Biodegradable and non-degradable wastes. Biodegradable wastes are generated by cotton Mills, food processing units, paper mills, and Textile factories. Non-biodegradable wastes are generated By thermal power plants which produce fly Ash; integrated iron and steel plants which Produce blast furnace slag and steel melting Slag. Industries manufacturing aluminium, Zinc and copper produce mud and tailings. Fertilizer industries produce gypsum. Hazardous wastes such as inflammables, Composite explosives or highly reactive Substances are produced by industries Dealing in metals, chemicals, drugs, pharma- Ceuticals, dyes, pesticides, rubber goods etc. The disposal of non-degradable industrial Solid wastes, if not done by a proper and Suitable method, may cause serious threat to The environment. New innovations have led to Different uses of waste material. Nowadays, Fly ash and slag from the steel industry are Utilised by the cement industry. Large quantities of toxic wastes are usually destroyed By controlled incineration, whereas small Quantities are burnt along with factory Garbage in open bins. Moreover, solid wastes If not managed effectively, affect the Components of the environment
Case Study – 5
Waste Management Solid waste is not the only waste, which you see in your household garbage box. Besides household discards, there are medical, agricultural, industrial and mining wastes. The improper disposal of wastes is one of the major causes of environmental degradation. Therefore, the management of wastes is of utmost importance.
The ‘Swachh Bharat Abhiyan’ or ‘Clean India Mission’ launched by the Government of India. Besides Two programmes are being implemented under the broad umbrella of the Swachh Bharat Abhiyan. These are Swachh Bharat Mission–Urban (SBM–U) and Swachh Bharat Mission Gramin (SBM–G). The SBM–U primarily aims at making Urban India free from open defecation and achieving 100% scientific management of solid waste in the country. The SBM–G targets to bring about an improvement in the general quality of life in rural areas by promoting cleanliness and hygiene, and eliminating open defecation. It is accelerating its efforts to achieve the goal of universal sanitation coverage by 2 October, 2019, which is the birth aniversary of Mahatma Gandhi.
Domestic wastes are collected in small bins, which are then transferred to community bins by private or municipal workers. From these community bins, these are collected and carried to the disposable site. At the site, garbage is sorted out and separated into biodegradable and non-biodegradable materials. Non-biodegradable materials such as plastic, glass, metal scraps etc. are sent for recycling. Biodegradable wastes are deposited in land fills and are converted into compost. The waste if not collected in garbage bins, finds its way into the sewers. Some of it is eaten by cattle. Non-biodegradable wastes like polythene bag, metal scraps, etc. choke the sewers and cause inconvenience. Polythene bags, if swallowed by animals can cost their lives also.
Green chemistry is a production process that would bring about minimum pollution or deterioration to the environment. The byproducts generated during a process, if not used gainfully, add to the environmental pollution. Such processes are not only environmental unfriendly but also cost-ineffective. The waste generation and its disposal both are economically unsound. Utilisation of existing knowledge base for reducing the chemical hazards along with the developmental activities is the foundation of green chemistry.
Green Chemistry in day-to-day Life
i) Dry Cleaning of Clothes- Tetra chlroroethene (Cl2C=CCl2) was earlier used as solvent for dry cleaning. The compound contaminates the ground water and is also a suspected carcinogen. The process using this compound is now being replaced by a process, where liquefied carbondioxide, with a suitable detergent is used. Replacement of halogenated solvent by liquid CO2 will result in less harm to ground water. These days hydrogen peroxide (H2O2) is used for the purpose of bleaching clothes in the process of laundary, which gives better results and makes use of lesser amount of water.
ii) Bleaching of Paper Chlorine gas was used earlier for bleaching paper. These days, hydrogen peroxide (H2O2) with suitable catalyst, which promotes the bleaching action of hydrogen peroxide, is used.
iii) Synthesis of Chemicals Ethanal (CH3CHO) is now commercially prepared by one step oxidation of ethene in the presence of ionic catalyst in aqueous medium with a yield of 90%.
iv) Green Solution’ to Clean Turbid Water Powder of kernel of tamarind seeds has been found to be an effective material to make municipal and industrial waste water clean. It is non-toxic, biodegradable and cost- effective material. This powder is usually discarded as agricultural waste. The present practice is to use alum to treat such water. It has been found that alum increases toxic ions in treated water and can cause diseases.
Green chemistry, in a nutshell, is a cost effective approach which involves reduction in material, energy consumption and waste generation.
[A] MCQ
1) The ‘Swachh Bharat Abhiyan’ or ‘Clean India Mission’ launched by the …
a) Government of India
b) Government of Maharashtra
c) Government of Kerala
d) Government of Goa
Ans- a) Government of India
2) … was earlier used as solvent for dry cleaning.
a) Dichlroroethene
b) Tetra chlroroethene
c) Trichlroroethene
d) chlroroethene
Ans- b) Tetra chlroroethene
3) SBM is accelerating its efforts to achieve the goal of universal sanitation coverage by …
a) 11 June , 2019
b) 19 June , 2019
c) 2 October, 2019
d) 1 November , 2019
Ans- c) 2 October, 2019
4) Which of the following programme is being implemented under the broad umbrella of the Swachh Bharat Abhiyan
a) SBM-U
b) SBM-G
c) SBM-M
d) both a) & b)
Ans- d) both a) & b)
5) … is used for bleaching of paper .
a) SO2
b) CO2
c) H2O2
d) NO2
Ans- c) H2O2
[B]Short Answers
1) Why waste management is important ?
Ans- Waste Management Solid waste is not the only waste, which you see in your household garbage box. Besides household discards, there are medical, agricultural, industrial and mining wastes. The improper disposal of wastes is one of the major causes of environmental degradation. Therefore, the management of wastes is of utmost importance.
2) Write short note on collection and disposal of domestic waste .
Ans- Domestic wastes are collected in small bins, which are then transferred to community bins by private or municipal workers. From these community bins, these are collected and carried to the disposable site. At the site, garbage is sorted out and separated into biodegradable and non-biodegradable materials. Non-biodegradable materials such as plastic, glass, metal scraps etc. are sent for recycling. Biodegradable wastes are deposited in land fills and are converted into compost. The waste if not collected in garbage bins, finds its way into the sewers. Some of it is eaten by cattle. Non-biodegradable wastes like polythene bag, metal scraps, etc. choke the sewers and cause inconvenience. Polythene bags, if swallowed by animals can cost their lives also.
3) What is green chemistry ?
Ans- Green chemistry is a production process that would bring about minimum pollution or deterioration to the environment. The byproducts generated during a process, if not used gainfully, add to the environmental pollution. Such processes are not only environmental unfriendly but also cost-ineffective. The waste generation and its disposal both are economically unsound. Utilisation of existing knowledge base for reducing the chemical hazards along with the developmental activities is the foundation of green chemistry.
[C]Long Answers
1) Give example of Green Chemistry in day-to-day Life .
Ans- Green Chemistry in day-to-day Life
1) Dry Cleaning of Clothes- Tetra chlroroethene (Cl2C=CCl2) was earlier used as solvent for dry cleaning. The compound contaminates the ground water and is also a suspected carcinogen. The process using this compound is now being replaced by a process, where liquefied carbondioxide, with a suitable detergent is used. Replacement of halogenated solvent by liquid CO2 will result in less harm to ground water. These days hydrogen peroxide (H2O2) is used for the purpose of bleaching clothes in the process of laundary, which gives better results and makes use of lesser amount of water.
2) Bleaching of Paper Chlorine gas was used earlier for bleaching paper. These days, hydrogen peroxide (H2O2) with suitable catalyst, which promotes the bleaching action of hydrogen peroxide, is used.
3) Synthesis of Chemicals Ethanal (CH3CHO) is now commercially prepared by one step oxidation of ethene in the presence of ionic catalyst in aqueous medium with a yield of 90%.
4) ‘Green Solution’ to Clean Turbid Water Powder of kernel of tamarind seeds has been found to be an effective material to make municipal and industrial waste water clean. It is non-toxic, biodegradable and cost- effective material. This powder is usually discarded as agricultural waste. The present practice is to use alum to treat such water. It has been found that alum increases toxic ions in treated water and can cause diseases.
2) Which programs launched by government of india for waste management ?
Ans- The ‘Swachh Bharat Abhiyan’ or ‘Clean India Mission’ launched by the Government of India. Besides Two programmes are being implemented under the broad umbrella of the Swachh Bharat Abhiyan. These are Swachh Bharat Mission–Urban (SBM–U) and Swachh Bharat Mission Gramin (SBM–G). The SBM–U primarily aims at making Urban India free from open defecation and achieving 100% scientific management of solid waste in the country. The SBM–G targets to bring about an improvement in the general quality of life in rural areas by promoting cleanliness and hygiene, and eliminating open defecation. It is accelerating its efforts to achieve the goal of universal sanitation coverage by 2 October, 2019, which is the birth aniversary of Mahatma Gandhi.