Composition Of Atmosphere Ok

Ch. No.1 INTRODUCTION

Classification of elements

The earth is more than 4500 million years old. The earth was formed from a cloud of dust and gases which cooled and formed a solidified crust. At that time the earth was much bigger and much cooler than it is now and had no atmosphere. Then it started contracting and became smaller and warmer. During this phase various gases were liberated from the earth and atmosphere was formed. The water vapour condensed to form rivers and seas. Oxygen was added to the atmosphere by the green plants (photosynthesis). Thus the atmosphere was formed which sustained life on earth. It extends up to about 40 km from the earth's surface. The region of air present around the earth is called atmosphere. The percentage of various gases in the atmosphere is generally fixed. The atmosphere gets polluted due to various activities taking place on the earth. Due to this, the various components and their amounts in the atmosphere get disturbed. Since pollution has a hazardous effect on the atmosphere, the chief priority of this century has been to identify the causes of pollution and take remedial measures to prevent pollution. Apart from the appropriate diet and need to exercise, the quality of our surroundings assumes paramount importance. The atmosphere of earth, of course, occupies the major part of our surroundings. In view of the great importance attributed to the study of atmosphere, the chapter 'revolves around the composition of atmosphere and the factors which affect the composition adversely. The various activities of humans generate different kinds of undesired, unsafe substances, which lead to pollution. Pollution is hazardous to life - human, plant as well as aquatic. The chapter begins with a brief explanation of the composition of the atmosphere. It then describes the basic facts about pollution. Going ahead, it discusses the different types of pollution, some case histories, and preventive measures. This chapter is significant since it deals with the factors that directly influence our lives.

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I. Define the following 1. Atmosphere: The envelope of gasses surrounding the earth is called the atmosphere. It extends up

to a height of about 40 km from the surface of the earth. 2. Acid rain:Nitrogen dioxide and sulphur dioxide present in air react with the moisture present in

the air and form nitric acid and sulphuric acid, respectively. These acids come down along with rain water. It is called acid rain. 3. Pollutant: The solid, liquid or gaseous substances present in such a large concentration, that it is

injurious to the environment and hazardous to life is called pollutant. 4. Pollution: The act of releasing a pollutant is called pollution. 5. Particulate pollutants: Solid pollutants in the form of fine particles suspended in air are called as

particulate pollutants. E.g. Fine particles of asbestos, carbon, etc. 6. Natural Pollutants: Pollen grains, spores and microbes present in excess are called natural

pollutants. 7. Radioactive pollutants: The radioactive harmful substances produced during nuclear testing,

nuclear explosions and testing of nuclear weapons are called radioactive pollutants. 8. Noise: Sound undesired by recipient is called noise. 9. Sound pollution: The continuous production of sound which is undesirable to its recipient is

called sound pollution. 2

10. Smog: The mixture of smoke and fog is called smog. It is fog carrying fine carbon particles. 11. Decibel: The unit of sound intensity is decibel.

II. Give scientific reasons: 1. The chimneys of the factories should be sufficiently tall. Ans. i. Toxic (poisonous, deadly) gases are discharged from the factories through the chimneys into the atmosphere. ii. The functions of a chimney are to discharge the pollutants at a high altitude. iii. So that they can disperse well and do not accumulate. Hence, the chimneys of the factories should be sufficiently tall. 2. Radioactive pollutants are the most dangerous. Ans. i. Radioactive pollutants mix with the atmosphere and remain in the atmosphere for a long time. ii. They effect human chromosomes and bring about permanent hereditary disorders. Hence, radioactive pollutants are most dangerous. 3. Air pollution is regarded as the most dangerous pollution. OR What are the most dangerous pollutants? Why? Ans. i. Man requires clean air for breathing. He cannot control the air he breathes. ii. Hence, if polluted air goes inside the body and affects the body adversely. Hence, air pollution is regarded as most dangerous. 4. Smog causes large number of road accidents. i. Smog is a mixture of smoke and fog. It is actually fog containing carbon particles. ii. It effects visibility and therefore causes large number of road accidents. 5. Ozone blanket is extremely important. Ans. i. The ultraviolet radiation coming from the sun is highly harmful to man. ii. The ozone layer absorbs the ultraviolet radiations coming from the sun. iii. It does not allow them to reach the earth surface. Hence Ozone blanket is extremely important. 6. Automobiles should be checked regularly. Ans. i. When the efficiency of automobile engine decreases, there is an incomplete combustion of the fuel. ii. It produces hydro – carbons and carbon monoxide. These are harmful pollutants. iii. Hence, automobiles should be checked regularly to examine the efficiency of their engines. 7. Trees act as bio – monitor for the problem of pollution. Or Trees should be planted along roadsides and residential areas. Ans. i. Green plants by photosynthesis produce food and release oxygen into air. 3

ii.

iii. iv.

These plants also keep the atmosphere moist by transpiration, which causes rainfall. Their roots keep soil compact. Their growth helps to reduce pollution. Hence, trees act as bio – monitor for the problem of pollution.

8. Carbon monoxide is a harmful pollutant. Ans. i. Carbon monoxide is the result of incomplete oxidation of the fissile fuels. ii. It permanently combines with haemoglobin and this reduces the oxygen carrying capacity of blood. iii. Therefore, carbon monoxide is a very harmful pollutant. 9. Workers in textile mills suffer from lung disorders on a large scale. Ans. i. Textile mills produce a lot of particulate pollutants like fibres. ii. These particulate pollutants are responsible for the causes of lung disorders. iii. Hence, the workers in textile mills suffer from lung disorders on a large scale. 10. House should be build away from the traffic roads. Ans. i. There is lot of vehicular activities on the traffic roads. ii. This gives rise to a lot of air pollution. iii. Air pollution is regarded as the most dangerous pollution. iv. Further, the vehicles are also responsible for sound pollution. v. Sound pollution is also harmful for the health. vi. Therefore, house should be build away from the traffic roads. 11. Workers in the factories should use earplugs and muffs. Ans. i. Factories are common places of sound pollution. ii. This affects the workers. iii. Prolonged (long-standing) exposure to sound pollution can cause permanent loss of hearing sense. iv. Therefore, workers in the factories should use earplugs and muffs to reduce the effect of sound pollution. 12. There should be proper legislation to control sound pollution. Ans. i. Sound pollution is very harmful. ii. It can cause damage to hearing. iii. Prolonged exposure to sound pollution can cause a permanent loss of hearing sense. iv. So, there should be proper legislation to control sound pollution. It is an important step to reduce sound pollution. 13. Silence zones should be declared near the hospitals. Ans. i. Noise pollution is harmful and gives rise to problems. ii. In the hospital areas, unwanted sound can give rise to irritation and headache. It will thus disturb the patients. iii. Therefore, hospital areas should be declared as silence zones. 14. It is dangerous to hear noise continuously. Ans. 4

i. ii. iii.

The immediate effect of loud noise is damage to haring. Prolonged exposure to loud noise can cause permanent loss of hearing sense. It also affects brain, liver and heart. Therefore, it is dangerous to hear loud noise continuously.

15. Pollution is a national problem. Ans. i. Many activities of human beings are responsible for changing the composition of our atmosphere. ii. Urbanisation, industrialisation and modern agricultural practices produce a variety of harmful substances and release them in our environment. Such substances are pollutants. iii. The pollution of atmosphere, water and soil produces harmful effects on the health of human beings. iv. In 1984, the MIC which was leaked from one insecticide factory at Bhopal killed over 3000 people and seriously affected many. The whole nation had to cope with this calamity. v. Hence, pollution is a national problem.

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III. Answer the following questions in short. 1. What are the effects of sound pollution on human health? Ans. Continuous loud sound affects human health as follows. i. Damage to hearing, which may lead to permanent loss of hearing. ii. Increase in the rate of heartbeats. iii. Dilation of the pupils of the eyes. iv. Increasing the digestive spasms. v. Bad effects on the brain, liver and heart. vi. Emotional disturbances. 2.

What are the sources of sound pollution? OR Write four causes of sound pollution. Ans. The sources of sound pollution are i. Household appliances like mixer, grinder, vacuum cleaner, washing machines, etc are responsible for sound of about 87 dB. ii. Loudly played radios and stereos, hi – fi loud speakers and T.V sets are other sources of sound pollution. iii. Quarrelling neighbours, shouting children, continuous ringing of bells and barking dogs also add to sound pollution. iv. Printing press, small industries produce sound of about 98dB. v. Vehicles like auto, trucks, motor – cycles, cars, trains and aero – planes (150 dB) equally contribute to sound pollution. 3. Ans. i. ii.

What is pollution? What are basic types of pollution? The act of releasing pollutant is called pollution. Fundamentally, there are three types of pollutions, they are a. Air pollution, b. Water pollution & c. Soil pollution.

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What are photochemical oxidants or Secondary pollutants? Name two of them. OR Write a short note on photochemical oxidants. Ans.The compounds formed by the reaction of nitrogen dioxide with hydrocarbons in air in the presence of light are called photochemical oxidants or secondary pollutant. The examples of photochemical oxidants are a. Ozone & b. PAN They are responsible for irritation of eyes, coughing, tired feeling and oedema. 5. Name any three pollutants of the atmosphere? Ans. The particulate pollutants of the atmosphere are Silica particles, Asbestos particles, Fibres.

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6.

What are radioactive pollutants? What are their sources Write a short note on radioactive pollutants.

OR

Ans. The harmful radioactive substances produced in nuclear explosions, nuclear testing and testing of nuclear weapons are called radioactive pollutants. Sources: Radioactive pollutants are produced in nuclear explosions, explosion of a nuclear reactor, nuclear tests and testing of nuclear weapons. Example: Strontium – 90, a by – product of nuclear tests. 7. What is the percentage of Nitrogen, Oxygen and Carbon dioxide in Air. Ans. The percentage of Nitrogen, Oxygen and Carbon dioxide in air are Particulars % Nitrogen 78.084 Oxygen 20.946 Carbon Dioxide 0.033 8. What is ozone layer? OR Write a short note on Ozone Layer. Ans. i. The layer of air between 16km to 23km from the surface of the earth in which there is a high proportion of ozone is called the ozone layer. ii. At about 16 km from the surface of the earth, the oxygen in the atmosphere is converted into ozone by the action of sunlight. iii. The proportion of ozone thus increases from about 16km to about 23km from the earth surface of the earth. 9. What is acid rain? Ans. Nitrogen dioxide and sulphur dioxide present in air react with the moisture present in the air and form nitric acid and sulphuric acid, respectively. These acids come down along with rain water. It is called acid rains 10. With the help of one example, explain the effect of acid rains. Ans. Nitrogen dioxide and sulphur dioxide present in air react with the moisture present in the air and form nitric acid and sulphuric acid, respectively. These acids come down along with rainwater. It is called acid rains.

Example: - Gaseous pollutants released from Mathura refineries near Agra are responsible for such acid rains. They have affected the famous Taj Mahal causing itching, this act is known as pitting. 11. How is pollution caused by the excess use of fertilizers? Ans. i. If phosphate and nitrate fertilizers are used in excess, they are washed off to the rear by lakes and ponds. ii. Here they lead to excessive growth of certain algae, iii. Thus, pollution is caused by the excess use of fertilizers.

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12. What is ''Bhopal Gas Tragedy.''? Ans.

On 3rd December, 1984, there was a leakage of the highly poisonous Methyl Isocyanate (MIC) gas from the storage tanks of Insecticide and Germicide factory (UNION Car – bide) at Bhopal in Madhya Pradesh. The MIC gas killed more than 3000 people and lakhs of people were seriously injured. This event is called a ''Bhopal Gas Tragedy''.

IV. Answer the following in briefly: 1. What are the control measures for air pollution? Ans. Following are the control measures for air pollution. 1. Tall Chimneys of factories help to discharge pollutants at the highest altitudes. 2. Automobiles should be checked regularly to control the level of poisonous gases released from the vehicle. 3. Green vegetation around the industry seems to be a good solution to reduce pollution. As trees act as bio monitor for the problem of pollution. 4. If use of a raw material produces more pollution, it should be replaced by a suitable one. For example, use of a fuel containing less percentage of sulphur. 5. Equipment in industry should be suitably modified to reduce or eliminate the pollution. 2. What are the health hazards of air pollution? Ans. health hazards of air pollution are 1. When sulphur dioxide is, present in air in excess it causes irritation of eyes, throat, bronchitis and other respiratory disorders. 2. Ozone and PAN are responsible for irritation of eyes, coughing, tired feeling, oedema etc. 3. Carbon monoxide combines with haemoglobin and reduces oxygen carrying capacity of the blood, which causes headache, dizziness, cardiac and pulmonary disorders. 4. Particulate pollutants are responsible for respiratory disorders like asthma and bronchitis. They cause skin diseases and allergic disorders. 5. Silica and asbestos particles cause fibrosis and are responsible for lung cancer. 6. Smog effects visibility, which causes a large number of road accidents. 3. List the causes of air pollution OR Find out the causes of air pollution in your surrounding. Ans. Causes of air pollution are: 1. Combustion of fossil fuels release oxides of sulphur and nitrogen. 2. Petroleum refineries release sulphur dioxide (SO2). 3. Power generators release nitrogen oxides. 4. Fertilizers and cold storage systems release ammonia., 5. Spraying and dusting on agricultural fields release organic phosphates and chlorinated hydrocarbons. 8

6. Fine Silica Particles, Asbestos Particles, Cotton fibres etc. present in air are some of the particulate pollutants. 7. Fine carbon particles are present in smoke and fog in air. 8. Pollen grains and spores present in air are natural pollutants. 4. What are the control measures for sound pollution? Ans. The control measures for sound pollution are 1. 2. 3. 4. 5. 6. 7.

Household appliances should be properly maintained. Use of sound absorbing materials. Vegetation buffer zones act as sound absorbing system. Sound limit should be prescribed for vehicles. There should be ban on honking horns. Silence zones should be declared near residential areas and schools as well as hospitals. People should be educated through various media like newspapers, radios, T.V & Inter net as regards to noise pollution. 8. Workers in the factories should use earplugs and muffs. 5. State the important constituents of atmosphere and mention their percentage / Proportion. Ans. At the earth’s surface the atmosphere consists mainly of nitrogen and oxygen. In addition to these gases small amount of carbon dioxide, water vapour, dust particles and rare gases are also present. The main constituents of the atmosphere are

Besides these gases, the atmosphere also contains neon, helium, methane krypton, hydrogen, nitrous oxide, xenon, water vapour and dust.

6. Write in brief the use of trees in decreasing the intensity of pollution. OR Explain the role of green plants in reducing environmental pollution. Ans. 9

i. ii. iii. iv.

Carbon dioxide is not required by human beings and the increase in the proportion of carbon dioxide leads to air pollution. Green plants require carbon dioxide for the preparation of their food (carbohydrates) through photosynthesis. This, green plants absorb carbon dioxide from air and give out oxygen which human being require for their respiration. Thus, green plants reduce the air pollution.

7. Describe the atmosphere of the earth with the help of the following points a. Four main constituents of the atmosphere b. Height of the atmosphere c. Height of ozone layer d. Formation of ozone layer and its function. Ans. Atmosphere: The envelope of gasses surrounding the earth is called the atmosphere. It extends up to a height of about 40 km from the surface of the earth. a. . At the earth’s surface the atmosphere consists mainly of nitrogen and oxygen. In addition to these gases small amount of carbon dioxide, water vapour, dust particles and rare gases are also present. The main constituents of the atmosphere are

b. Atmosphere extends up to a height of about 40 km form the surface of the earth. c. From 16 to 23 km there is an ozone layer. d. At about 16 km from the surface of the earth, the oxygen in the atmosphere is converted into ozone by the action of sunlight. The ozone layer absorbs harmful ultraviolet radiations form coming from the sun. 8. Explain the pollution caused by bursting crackers in celebrations OR What are the effects of human life of sound and air pollution in festival due to crackers? Ans. Bursting of crackers in festivals leads to two types of pollution i. Sound Pollution: - The loud sound of the crackers leads to sound pollution. It will have bad effects on heart, lung and liver of human beings. It leads to dilation of pupils of the eyes and emotional disturbances. ii. Air Pollution: - Due to combustion of the ingredients of crackers, poisonous gases like, CO, SO2, NO2, etc. are generated. These gases produce respiratory disorders. [ Note: - During any celebrations generally a lot of crackers are lit off. This produces a lot of unwanted sound in the range above 140 dB. This becomes a source of unwanted sound and results in sound pollution. This can cause damage to hearing and emotional disturbance. Therefore bursting crackers during any celebration should be avoided]

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9. Write a short note on: - Green House effect. Ans. It is a warming near the earth's surface that results when the earth's atmosphere traps (lock in) the sun's heat. The earth's atmosphere traps allows most of the sunlight that reaches it to pass through and heat the earth's surface. The earth sends the heat energy back into the atmosphere. Much of these rays do not pass freely into space, because certain gases in the atmosphere absorb it. These gases include CO2, O3 and water vapour. They grow warm and send rays back towards the earth, adding to the warming at the surface. Green house effect received its name because the earth's atmosphere acts much like the glass/ plastic roof and walls of a green house. Sunlight enters a green house through the glass or plastic and heats the interior. The roof and walls slow the escape of the heat. 10. Tell the types of pollution involved and their effect on human health. a. Acid rain in Agra. b. Leakage of MIC at Bhopal c. Atomic blast on Hiroshima and Nagasaki d. A procession with loud orchestra passes by a hospital. Ans. a. Acid rain in Agra: - It is an air pollution. The acid rain in Agra affects the world famous Taj Mahal

causing itching. b. Leakage of MIC at Bhopal: - It is air pollution. The leakage of MIC from the storage tank of an

insecticide and germicide factory at Bhopal killed over 3000 people and seriously affected nearly a lakh of residents. c. Atomic blast on Hiroshima and Nagasaki: - It is a radioactive pollution. Due to the atomic blast on Hiroshima nearly one lakh people dead. Many hereditary disorders were observed later on. The after effects are still observed in Japan. d. Procession with a lour orchestra passes by a hospital: - It is a sound pollution. Due to the loud sound in the orchestra, the patients in the hospital may experience dilation of pupils of the eyes, effects on their heart, increase of digestive spasm and emotional disturbances.

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