Composition Of Atmosphere

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

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atmosphere. It extends up to a height of about 40 km from the surface of the earth. 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. 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. Pollution: The act of releasing a pollutant is called pollution. 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. Natural Pollutants: Pollen grains, spores and microbes present in excess are called natural pollutants. Radioactive pollutants: The radioactive harmful substances produced during nuclear testing, nuclear explosions and testing of nuclear weapons are called radioactive pollutants. Noise: Sound undesired by recipient is called noise. Sound pollution: The continuous production of sound which is undesirable to its recipient is called sound pollution. Smog: The mixture of smoke and fog is called smog. It is fog carrying fine carbon particles. 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.

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Air pollution is regarded as the most dangerous pollution. What are the most dangerous pollutants? Why?

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Man requires clean air for breathing. He cannot control the air he breathes. 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. Ans. i. Green plants by photosynthesis produce food and release oxygen into air. ii. These plants also keep the atmosphere most by transpiration, which causes rainfall. iii. Their roots keep soil compact. Their growth helps to reduce pollution. iv. Hence, trees act as bio – monitor for the problem of pollution.

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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. Quarreling neighbors, 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.

4. 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 odema.

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5. Name any three pollutants of the atmosphere? Ans. The particulate pollutants of the atmosphere are Silica particles, Asbestos particles, Fibres. 6.

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

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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.

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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, odema 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. 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. 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.

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4. What are the control measures for sound pollution? Ans. The control measures for sound pollution are 1. 2. 3. 4. 5. 6.

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. 7. 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. Following tables gives the composition of the stable constituents in the atmosphere at the surface of the earth. Particulars Nitrogen Oxygen Argon Carbon dioxide

% 78.084 20.946 0.934 0.033

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

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