Environmental Chemistry

Greenhouse gas is a gas that contributes to the greenhouse effect by absorbing infrared radiation.

Among the following option, O₃, CH₄ and H₂O vapour are the greenhouse gas and CO is not because of CO absorbs low energy of infrared.

But CO can be put it in an indirect column of greenhouse gas because it increases the concentration of other greenhouse gases.

Photochemical smog is a type of smog produced when ultraviolet light from the sun reacts with nitrogen oxides in the atmosphere. It is visible as a brown haze, and is most prominent during the morning and afternoon, especially in densely populated, warm cities

The main components of photochemical smog are nitrogen oxides, Volatile Organic Compounds (VOCs), tropospheric ozone, and PAN (peroxyacetyl nitrate).

Among the following options, NO₂, O₃ and unsaturated hydrocarbon are components of photochemical smog where they required a warm, dry and sunny climate to get oxidized. SO₂, on the other hand, has a reducing nature. Hence cannot be the component of photochemical smog.

Classical smog is a mixture of sulfur dioxide and coal smoke with fog. It is called London smog because of an incident which was took placed in 1952 which was known as the Great Smog of London.

(ii) It is indeed produced in a cold and humid climate because the components which are present are of reducing nature. And sunlight is not required as here oxidizing is not taking place.

(iii) It contains compounds of reducing nature.

(iv) Classical smog results from large amounts of coal burning in an area and is caused by a mixture of smoke and sulfur dioxide. Hence, indeed it contains smoke, fog and sulphur dioxide.

On the other hand, (i) is not true for classical smog as it doesn’t require the action of sunlight, etc.

BOD value less than 5 ppm indicates a water sample to be pure because BOD is a measurement of organic waste present in water. If BOD is more than 5 ppm then it indicates more organic waste, leading dissolved oxygen to be less because of usage of oxygen in the degradation of organic waste by microbes.

On the other hand, (ii),(iii),(iv) are elucidating to the polluted water, anti to what has explained above, making them wrong.

Greenhouse gas is a gas that contributes to the greenhouse effect by absorbing infrared radiation.

Ozone, high in the stratosphere, absorbs ultraviolet light from the sun and protects the earth. It is a greenhouse gas and it is responsible for the greenhouse effect.

On the other hand, (ii),(iii),(iv) are the wrong statements.

Due to the increase in organic waste, BOD value increases and dissolved oxygen, making fishes die due to less oxygen.

(i) It can not be a reason for fishes die in water as there is nothing to do with a large number of mosquitoes. Both can live independently.

(ii) This second statement cannot be a reason too as it is a false statement. Due to organic waste, dissolved oxygen actually decreases.

(iv) It is a false statement as mud cannot be a reason for the clogging of gills. It is sedimentary pollution that causes fish gills to be clogged.

Photochemical smog is a haze in the atmosphere accompanied by high levels of ozone and nitrogen oxides, caused by the action of sunlight on pollutants.

Here components of it have a high concentration of oxidising agents. Moreover, pinus release various volatile organic gases which get reacted with components of photochemical smog and reduces the ambient concentration of ozone, NO₂, hydrocarbon, etc.

Troposphere is the lowest layer of the atmosphere. It extends upward to about 10km above sea level. And it is followed by another layer named stratosphere and then mesosphere. The hydrosphere includes water that is on the surface of the planet, underground, and in the air.

In the environment, 78% of dinitrogen gas and 21% of dioxygen gas is present still cannot react because the reaction is endothermic and requires very high temperature. Nitrogen oxide is formed at a very high temperature.

(ii) The catalyst lowers the energy of formation. Here only in the presence of a catalyst, the reaction cannot be initiated.

(iii) Oxides of nitrogen like NO₂ is resonance stabilized and some others are relatively unstable.

Peroxyacetyl nitrates (PANs) are produced in the atmosphere when oxidized volatile organic compounds combine with nitrogen oxide. They are secondary pollutants because they formed after the emission of primary pollutants.

(i),(ii) cannot be correct as ozone does not ooze out from the stratosphere or troposphere respectively.

(iv) cannot be correct because the ozone hole does not mean the vanishing of the ozone layer around the earth completely. The ozone hole is thinning of the ozone layer of the stratosphere at some places.

Green chemistry is a way of thinking and is about utilizing the existing knowledge and principles of chemistry and other sciences to reduce the adverse impact on the environment.

As we know plastic is a non-biodegradable waste so using it, will not reduce the adverse impact on the environment.

More than BOD 5 ppm in water means the water is polluted and eutrophication itself leads to loss of biodiversity, killing fishes and various creatures living inside water. Hence iii, iv shows polluted environment.

•Addition of Phosphate containing fertilisers in water bodies cause water pollution due to enhanced growth of algae.

•Due to that oxygen concentration decreases in water.

Acid rain is a by-product of a variety of human activities that emit the oxides of sulphur and nitrogen in the atmosphere.

2SO₂ (g) + O₂ (g) + 2H₂O (l) → 2H₂SO₄ (aq)

4NO₂ (g) + O₂ (g) + 2H₂O (l) → 4HNO₃ (aq)

so the end product is (iii, iv)

Consequences of global warming lead to an increase in the average temperature of the earth and thus melting of Himalayan glaciers also gets into the picture.

Sun radiation is trapped by gases such as carbon dioxide, methane, ozone, chlorofluorocarbon compounds (CFCs) and water vapour which are all greenhouse gases that are responsible for the greenhouse effect leading to global warming.

When pH of rain water is below 5.6 then it is acid rain. Acid rain is a by-product of a variety of human activities that emit the oxides of sulphur and nitrogen in the atmosphere.

2SO₂ (g) + O₂ (g) + 2H₂O (l) → 2H₂SO₄ (aq)

4NO₂ (g) + O₂ (g)+ 2H₂O (l) → 4HNO₃ (aq) . Nitric acid and sulphuric acid are acids present in acid rain.

The UV radiation is harmful to any living species because it causes mutagens in our cells, skin cancers, melanoma, and many other diseases. Ozone in the stratosphere absorbs this UV radiation from the Sun and does not let pass it to the inner atmosphere. If ozone from this region is completely removed, many health issues will be encounter.

Eutrophication is the process responsible for the reduction of dissolved oxygen in the water. It is a process in which nutrient-enriched water bodies support a dense plant population, which kill animal life by depriving of oxygen and result in subsequent loss of biodiversity.

In the stratosphere due to the action of U.V rays causes the dissociation of cloroflorocarbons to realese the free chlorine radicle as shown in the equation below:

CF₂Cl₂ + U V radiations → Cl + CFCl

Now this Chlorine radicle so formed is free and in the stratospheric layer reacts with the Ozone to form Chlorine monoxide and oxygen as shown in the equation below:

Cl (g) +O₃ (g) → ClO (g)+O₂(g)

Now further the reaction of chlorine monoxide with the nascent oxygen ie. Oxygen atom leads to the formation of oxygen and again chlorine free radical is formed as shown in the equation below:

ClO (g) + O (g) →Cl + O₂

This way Chlorine radicles are being regenerated and are reacting with ozone layer. So, CFCs are considered as the source of chlorine radicles which are destroying the ozone layer of stratosphere.

The improper disposal of waste materials is the major source or cause of environment pollution. If the domestic waste is not disposed of properly it leads to the following problems:

• Domestic waste means the household wastes which if not disposed of properly leads to chokage of sewer lines.

• Choking of sewage lines leads to the stagnation of sewage water which may become the breeding ground for the pathogenic mosquitoes.

• Imroper disposal of house hold waste which includes nonbiodegradable waste like glass, polythene in open grounds may lead to the chokage of gut of the cattle which may happen to eat the polythene along with food which may even lead to death of such organisms.

• Improper management of such domestic wastes contributes to soil pollution to a large extent.

Improper disposal or management of industrial waste is major cause of soil, water and air pollution.

Soil pollution is caused by the dumping of harmful chemicals generated by industries which penetrates in soil and get mixed with ground water.

Water pollution is caused by directly by disposing the used water waste from industries to rivers or ponds.

Air pollution is caused by the harmful smokes being generated by industries pollutes the fresh air of the atmosphere.

The reason for the destroyed condition of lake was due to the disposing of the domestic waste generated in the houses of vilaggers and organic compounds like detergent in the lake Can provide nutrients for the rapid growth of algae and the aquatic plants and the decomposition of these with the help of bacteria produces foul smell. With the time the concentration of the nutrients in the lake increases. This development of plants in nutrient rich lake is due to the process called eutrophication.

Biodegradable pollutants.

Pollutants which are easily decomposed by the bacteria or other microorganisms or by various environmental factors like waste of vegetables fruits, sewage, cow dung etc are called as biodegradable pollutants.

Non biodegradable pollutants.

Pollutants which are not easily decomposed by the bacteria or any other environmental factors and remains as such in the environment and pollutes it eg polythene, DDT, mercury, aluminium etc are called as non biodegradable pollutants.

Main sources of dissolved oxygen in water are:

• Oxygen reaches the water through the atmosphere where there is direct contact of water with atmospheric air.

• By photosynthesis through green aquatic plants in the presence of day light. In night the photosynthesis does not take place but the plants respire but the amount of oxygen is reduced.

• By mechanical aeration.

Biochemical oxygen demand (BOD) is defined as the amount of oxygen required by the bacteria to decompose the organic.

matter present in the certain volume of sample water.

Higher the BOD of water highly polluted is the water. Lesser the BOD of water less polluted is the water.

Drinking water have BOD of the range of less than 5ppm and highly polluted water have BOD of the value of 17ppm or more.

Contamination of water or any water bodies with the high amount of phosphate from the inflow of agricultural waste water polluted with fertilizers and pesticides and the disposing off the industrial waste water can contaminate the water with phosphates which leads to the rapid growth of algae in the water, turning the water and water body whole green is called Algal bloom. The decomposition of algae by the bacteria continuously produces foul smell and the algae makes water polluted and undesirable. The amount of dissolved oxygen also decreases and can lead to death of aquatic animals.

The symptoms observed in the village people are same caused when there is the presence of oxides of nitrogen and sulphur in the atmosphere. These oxides are produced by the industriesthrough oxidation of fossil fuels like coal gasoline etc.

The fossil fuels containing nitrogen burns in presence of oxygen to produce a variety of oxides of nitrogen as shown in the equation below:

N₂ (g) + O_{2 (g)} → 2 NO (g)

2NO (g) + O₂ (g) → 2 NO₂

The fossil fuels containing sulphur also burns in air containing oxygen to produce oxides of sulphur causing various breathing problems.

S + O₂ → SO₂

These oxides produced by the industries comes out to atmospheric air through chimneys causing air pollution and breathing problem for living beings.

Uncatalysed reaction of oxidation of sulphur dioxide to sulphur trioxide is very slow. But in the atmosphere the sulphur dioxide is easily being oxidised to sulphur trioxide because the air in the atmosphere contains particulate matter which acts as a catalyst for the oxidation reaction.

2SO₂ (g) + O₂ (g) → 2SO₃ (g)

For eg the reaction can also be promoted by the the presence of ozone and hydrogen peroxide the oxidation of sulphur dioxide takes place as according to the given equations:

SO₂ (g) + O_{3 (}g) → SO₃ (g) +O₂ (g)

SO₂ (g) + H₂O₂ (L) → H₂SO₄ (aq)

The composition of photochemical smog is nitrogen oxides, Volatile organic compounds (VOC), ozone, PAN i.e. peroxyacetyl nitrate.

Now the nitrogen oxide present in the smog undergoes dissociation in the presence of sunlight to NO and nascent oxygen (O) .as shown in the reaction below:

NO₂ (g) → NO (g) + O (g)

The nascent oxygen is very reactive and reacts with the oxygen gas to form Ozone gas along with the inert gas which promotes their reaction. After the reaction inert gas is obtained as it is without reacting with any of the species. As depicted by the reaction below:

O (g) + O_{2 (g)} + M → O₂ (g) + M

Where M = inert gas.

Ozone layer is formed in the stratosphere by the action of U. V radiations on the atmospheric oxygen. UV radiations causes the splitting or dissociation of molecular oxygen to two oxygen atoms as shown below in the reaction:

O ₂ (g) → O (g) + O (g)

Now the oxygen atom combines with other molecular oxygen to form Ozone as shown in the equation below:

O (g) + O₂ (g) → O₃ (g)

Ozone layer is heavier than oxygen and is thermodynamically unstable and there is a dynamic equilibrium in the reaction between formation and dissociation of the ozone as shown:

O₂ (g) → O (g) + O (g)

O (g) + O₂ (g) → O₃ (g)

(reaction is in dynamic equilibrium)

Since it’s thermodynamically unstable so it does not settle down near the earth.

Scientists working in the Antarctica reported the depletion of ozone layer called ozone hole over the south pole of the Antarctica. This time the depletion was reported due to unique set of conditions. In the summer season the nitrogen dioxide and methane reacted with the chlorine monoxide and chlorine radicle respectively forming chlorine sinks thereby preventing the depletion of ozone.

ClO + NO₂ (g) → ClONO₂

Cl (g) + CH₄→ CH₃(g) + HCl (g)

ClONO₂ (g) +H2O → HOCl (g) + HNO₃

ClONO₂ (g) + HCl → Cl₂ (g) + HNO₃ (g)

Wherease in winters the formation of polar stratospheric clouds was observed over the entire Antarctic region. These clouds were reported to act as a surface over where the chlorine nitrate formed got hydrolysed to form hypochlorous acid. The acid thus formed reacted with hydrogen chloride to form molecular chlorine.

HOCl (g) → OH (g) Cl (g)

Cl + Cl Gives molecular chlorine

When the sunlight returned back in the spring it led to breaking up of clouds and HOCl and molecular chlorine gets photolysed by sunlight to form chlorine radicles as shown below:

Cl₂ (g) → 2 Cl

These chlorine radicles further caused the ozone depletion.

Laxative effect is the effect caused by laxative substances that loosen stools and increases bowel movement. High doses of laxatives may even cause diarrhea.

Study on it reported that the presence of excessive sulphate (greater than 500 ppm) in the drinkingwater is the major cause of it. When sulphate is present in moderate amounts it is harmless.

Match it

(i) Oxides of sulphur - (d) Respiratory diseases

Explanation:Oxides of sulphur are produced when sulphur-containing fossil fuel is burnt. The most poisonous gas is sulphur dioxide which in low concentrations can cause respiratory diseases like asthma, bronchitis, emphysema in human beings.

(ii) Nitrogen dioxide - (e) Red haze in traffic and congested areas

Explanation:The irritant red haze in the traffic and congested places is due to oxides of nitrogen. Nitric oxide reacts with oxygen instantly to give nitrogen dioxide and the rate of nitrogen dioxide is faster when nitric oxide reacts with ozone in the stratosphere.

(iii) Carbon dioxide - (a) Global warming

Explanation:Carbon dioxide is released into the atmosphere by numerous ways which include respiration by animals and plants, fossil fuels burning for retrieval of energy and by decomposition of limestone during the manufacturing of cement. Deforestation and burning of fossil fuel increase the Carbon dioxide level and disturb the balance in the atmosphere. Carbon dioxide is mainly responsible for causing and promoting global warming.

(iv)Nitrate in drinking water -(c) ‘Blue baby’ syndrome

Explanation:Purified or clean drinking water is generally used for various purposes which include – drinking, cooking or cleaning etc. so as to avoid the occurrence of any kind of diseases. According to the International Standards, the maximum limit of nitrate that can be present in drinking water is 50ppm. On the other hand, excess nitrate in drinking water can lead to cause methemoglobinemia or commonly called as ‘blue baby syndrome’.

(v) Lead - (b) Damage to kidney

Explanation:Hygiene is of prime importance. To stay fit and fine we must drink and eat hygienic, covered, clean and nutritious food/water. Sometimes, if we consume contaminated water/food we acquire various diseases.According to the International Standards, the upper limit of concentration of lead in drinking water is to be 50 ppb. Otherwise, Pbcan cause variousproblems kidney, liver, reproductive system etc.

(i) Releasing gases to the atmosphere after burning waste material containing sulphur - (e) Classical smog,acidrain, water pollutioncleaning computer parts induce problems, damage tobuildings, corrosion of metals.

Explanation: Releasing gases to the atmosphere produced by automobiles and factories may cause classical smog, acid rain and induce problems, damage to buildings and corrosion of metals. Classical smog is one of the pollutants which occurs in cool and humid climate. It is of reducing in nature.

(ii) Using carbamates as pesticides - (d) May cause nerve diseases in human.

Explanation:Carbamates and organo-phosphates are bio-degradable products and less persistent. These chemicals are severe nerve toxins and hence more harmful to humans and could lead to death.

(iii) Using synthetic detergents for layer washing clothes - (a) Water pollution

Explanation:Use of synthetic detergents for washing clothes may lead to water pollution and depletion of fresh water.

(iv)Releasing gases produced byautomobiles and factoriesin the atmosphere - (b) Photochemical smog, damageto plant life, corrosion to building material, induce breathing problems, water pollution

Explanation: Photochemical smog occurs in warm, dry 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. It has high concentration of oxidising agents and damage plant life. It also causes corrosion of metals, stones, building materials, rubber and painted surfaces. It is of oxidising in nature and occurs in dry and sunny climate.

(v) Using chlorofluorocarbon compounds - (c) Damaging ozone layer

Explanation:The main reason for ozone layer depletion is due to the release of Chlorofluorocarbons (CFCs), also commonly referred to as freons. These compounds are non-reactive, non-flammable, non-toxic organic molecules and therefore, used in refrigerators, air conditioners and for cleaning computer parts.

(i) Phosphate fertilisers in water - (d) Eutrophication

Explanation:Phosphate fertilisers in water can enhance algal growth which could cover the water surface and reduces the oxygen concentration in the water. This leads to anaerobic conditions, commonly with accumulation of decay and animal death. This algal bloom inhibits the growth of other living organisms in the water body. This process is called eutrophication.

(ii) Methane in air - (c) Global warming

Explanation:Methane is produced naturally when vegetation is burnt, digested or rotted in the absence of oxygen. Large amounts of methane are released from paddy fields, coal mines and by fossil fuels. It contributes to global warming.

(iii) Synthetic detergents in water - (a) BOD level of water increases

Explanation:Synthetic detergents in water could result in reduction of dissolved oxygen and therefore, increase in BOD level of water. The amount of BOD in the water is a measure of amount of organic material in the water.

(iv) Nitrogen oxides in air – (b) Acid Rain

Explanation:Acid rain is a by-product of a variety of human activities that emit the oxides of sulphur and nitrogen in the atmosphere. Acid rain is harmful for agriculture, trees and plants as it dissolves and washes away nutrients needed for their growth. It causes respiratory ailments in human beings and animals. When acid rain falls and flows as ground water to reach rivers, lakes etc. it affects plants and animal life in aquatic ecosystem.

(i) Both A and R are correct and R is the correct explanation of A.

Explanation:Sun is the major source of light energy and it is required by all the organism for sustaining their lives. The Sun radiates its rays which enter into the Earth’s atmosphere but due to the presence of ozone, it doesn’t able to escape. This results in the increase of the temperature inside the Earth. This is known as Greenhouse Effect. In the greenhouses the factors which regulate or drive the normal physiological processes/functioning of the plants get accelerated. Temperature (controlled by heaters or fans etc), humidity, soil aeration, irrigation, fertility levels and controlled light amounts are required for the optimum growth of plants. Therefore, plants are able to grow properly and yield more amount of biomass due to the availability of these safe and protected conditions.

The greenhouses are generally transparent buildings or big rooms which are made up of glass (PMMA/ acrylic glass)or green glassor plastic (polyethylene film) or polycarbonate material multiwall sheets which are used to trap the radiations coming from the Sun. Green glass is composed of chrome oxide (different concentrations give variations in green color). Thus, to give a typical green color, they are composed of green glass.

(ii) Both A and R are correct but R is not the correct explanationof A.

Explanation:Acid rain is the rain which has been acidified by the chemicals present in the atmosphere. Due to the presence of pollutants or chemicals released from the industry (industrial smoke) or vehicular exhaust like sulphur oxides and nitrogen oxides, they react with the water vapours or water droplets andform acids of respective non-metals which in turn results in thelowering of the pH of the rain. Sometimes, carbon dioxide present in the atmosphere can also lead to lowering of pH of rain, but it isnot the sole factor responsible for lowering the pH of rain to less than 5.6.

(i) Both A and R are correct and R is the correct explanation of A.

Explanation: Photochemical smog is one of the types of pollution which generally results from the reaction of atmospheric chemicals and sunlight. The primary Photochemical smog component is the ozone along with this it also contains , acrolein, PAN (Peroxy Acetyl Nitrate) and volatile organic compounds like formaldehyde.

The formation of photochemical smog involves multiple reversible oxidation/reductions steps of nitrogen oxides, methane and sulphur oxides.

Now, both nitrogen dioxide and ozone acts as oxidising agents and react with unburnt hydrocarbons and produce other components of photochemical smog – PAN, formaldehyde and acrolein.

(i) Both A and R are correct and R is the correct explanation of A.

Explanation:Carbon dioxide is one of the main components and important greenhouses gases. Gases like methane, carbon dioxide and nitrous oxide absorb the UV radiations and prevent them from escaping from the Earth’s atmosphere, thus leading in the increaseof the temperature of the Earth’s surface which is essential for the sustenance of life. All living organism exhale carbon dioxide during the respiration process which in turn leads to the accumulation of in the atmosphere. On the other hand, increasing concentration of carbon dioxide leads to global warming as well. Therefore, the proportion of in the atmosphere should be maintained.

(i) Both A and R are correct and R is correct explanation of A.

Explanation: Ozone formation takes place in the stratosphere when dioxygen reacts with free Oxygen in the presence of intense UVradiations. This ozone layer protects the Earth from the harmful radiations coming from the Sun, otherwise which cause several severe medical problems like melanoma (skin cancers) inhumans. At the same time, ozone is unstable thermodynamically,therefore, as soon as it is formed it gets decomposed tomolecular oxygen in the stratosphere. Although, this process of decomposition is being accelerated due to the usage of various anthropogenic activities or release of CFCs/freons. These chemicals are used in refrigerators, ACs etc and are non-reactive, non-toxic and non-flammable to humans but still due to the ability to produce Cl radicals continuously upon reacting with UV in the stratosphere, they contribute in the depletion or thinning ofthe ozone layers.

This reaction takes place continuously thereby resulting in destroying or scavenging ozone molecules. Thus, leading to thinning of ozone layer.

(i) Both A and R are correct and R is the correct explanation of A.

Explanation: Excessive use of chlorinated synthetic pesticides causes soil and water pollution. This is due to the fact that fertilizers slowly get accumulated in the water bodies and start hindering with others too. This in turn cause several problems as they start migrating from one place to other water bodies with the help of rain. Also, pesticides are chemicals which can not be decomposed or degraded using the microorganisms. Therefore, they are non-biodegradable.

(iii) Both A and R are not correct.

Explanation:BOD value is more than 17 ppm for the more polluted water bodies whereas it is less than 5 ppm for the clean water bodies. Biological Oxygen Demand is defined as the amount of oxygen required by the bacteria to break down the organic matter into simpler compounds. Further, the BOD value is directly related with the amount of organic matter present in the water sample which is available for the bacteria to break upon. Therefore, high biological oxygen demand value means high activity of bacteria in water.

(i) The primary precursors of photochemical smog can be controlled which consists ofcompounds as Nitrogen dioxide and hydrocarbons, the secondary precursors such as ozone and PAN, the photochemical smog will automatically be reduced. Usually, catalytic converters are used in automobiles, which prevent the release of nitrogen oxide and hydrocarbons to the atmosphere. Certain plants e.g., Pinussp., Juniparussp., Quercussp., Pyrussp. and Vitissp.can metabolise nitrogen oxide and therefore, their plantation could help in this matter.

(ii) Tetra Chloroethene is now being replaced by a process, where liquefied Carbondioxide, with a suitable detergent, is used. Replacement of halogenated solvent by liquid will result in less harm to groundwater. These days hydrogen peroxide () is used for the purpose of bleaching clothes in the process of laundry, which gives better results and makes use of a lesser amount of water. Chlorine gas was used earlier for bleaching paper. These days, hydrogen peroxidewith a suitable catalyst, which promotes the bleaching action of hydrogen peroxide, is used.

(iii) Synthetic detergents are salts of Na having long chains of Benzene sulphonic acids or salts of Na having long chains of alkyl hydrogen sulphates. But unlike, other pollutants, detergents are not biodegradable as they are not acted upon by microorganisms. Due to the presence of Mg or Ca salts they are not easily degraded and they form bubbles in water where oxygen and sunlight gets tapped and they hinder the normal growth of the planktonic species growing in the water. Thus, the use of synthetic detergents should be reused.

(iv) The consumption of petrol and diesel should be reduced being fossil fuels, they release compounds containing sulphur (mainly sulphur dioxides) which get released in the atmosphere and comes on the ground in the form of acid rain by forming respective acids.

Therefore, they should be replaced by bio-diesel and bio-petrol so that environmental pollution can be controlled. These are made using green chemistry (by using plant-based materials) and eco-friendly.

Carbon dioxide is released into the atmosphere by various processes like respiration and burning of fossil fuels for energy, etc.

This gas is also emitted during volcanic eruptions. Carbon dioxide gas is normally found till troposphere. As the consumption of fossil fuels increases, a large amount of carbon dioxide gets released into the atmosphere. Excess of in the air is removed by green plants and this maintains an appropriate level of in the atmosphere. Green plants require for photosynthesis and they, in turn, emit oxygen, thus maintaining the delicate balance deforestation and burning of fossil fuel increases the level and disturb the balance in the atmosphere.

The increased amount of in the air is responsible for global warming. About75% of the solar energy reaching the earth is absorbed by the earth’s surface, which thereby increases the temperature. The rest of the heat radiates or reflects back in to the atmosphere. Some of the heat is trapped by gases such as , Methane, chlorofluorocarbon compounds (CFCs) and water vapour in the atmosphere.

Thus, they add to the heating of the atmosphere. Carbon dioxide molecules trap heat as they are transparent to sunlight but not to the heat radiation. If the amount of carbon dioxide crosses the delicate proportion of 0.03%, the natural greenhouse balance may get disturbed. Carbon dioxide is the major component which contributes to the global warming.

The glass in a greenhouse holds the sun’s warmth inside same as the 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.

In a greenhouse, solar radiations pass through the transparent glass and heat up the soil and the plants. The warm soil and plants emit infrared radiations. Since glass is opaque to infrared radiations (thermal region), it partly reflects and partly absorbs these radiations. This mechanism keeps the energy of the sun trapped in the greenhouse. Similarly, carbon dioxide molecules also trap heat as they are transparent to sunlight but not to the heat radiation. Carbon dioxide is the major contributor to global warming.

The fishes were not fit for human consumption because large amount of pesticides had accumulated in the tissues of fishes as a result of biomagnification.Biomagnification is the process in which the pesticides get slowly accumulated in the fishes or other marine animals thereby results in the decline of other species which feed on them.

Tetrachloroethylene is widely used for dry-cleaning fabrics and metal degreasing operations. Acute or short term high-level inhalation exposure of humans to tetrachloroethylene effects include irritation of the upper respiratory tract and eyes, kidney dysfunction, and neurological effects such as reversible mood and behavioral changes, impairment of coordination, dizziness, headache, sleepiness, and unconsciousness.

While the primary effects of chronic (long term) inhalation exposure involve neurological, including impaired cognitive and motor neurobehavioral performance. Tetrachloroethylene exposure may also cause adverse effects in the kidney, liver, immune system, and on development and reproduction.

Use of liquefied Carbon dioxide along with detergent will not be completely safe because most of the detergents are non-biodegradable and they cause water pollution. Moreover, liquefied
carbon dioxidewill ultimately enter into the atmosphere and contribute to the greenhouse effect. These days hydrogen peroxide is used for bleaching clothes in laundries for better quality and saves water.