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GURUKUL CENTRAL ACADMY, CH.- 18- POLLUTION OF AIR AND, WATER, WORKSHEET-1, Refer text book, WORKSHEET-2, Refer text book, , TEXTBOOK EXERCISES, Page 204 Try These, 1. pollutants 2. chlorosis 3. ozone, 4. Marble cancer 5. CNG, unleaded petrol, Page 209 Try These, 1. F, , 2. T 3. F 4. F 5. T, , EXERCISES, A. 1. a., B. 1. – c., C., , 2. d., , 3. b., , 2. – d., , 4. b., , 5. a. 6. d. 7. d. 8. a., , 3. – a. 4. – e., , 5. – f., , 6. – b., , 1. Volcanic eruptions, forest fires 2. poisonous gas, 3. acid rain 4. Increase 5. oil spills 6. Rainwater harvesting

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GURUKUL CENTRAL ACADMY, D., , E., , 1. Soil particles, plant spores, processing of minerals, 2. Ozone, 3. Carbon dioxide, methane, nitrous oxide, water vapour, 4. Spring, tube wells, 5. Algal bloom, 6. City waterwoks, 1. It makes the nature poisonous and reduces the oxygen, carrying capacity of the blood., 2., , 3., , 4., , 5., , 6., , When the addition of unwanted substances contaminate the, air such that, it has a harmful impact on both living and nonliving things, it is called air pollution. Sulphur dioxide and, nitrogen dioxide, Refrigerators, air conditioner and aerosol sprays. They, damage the ozone layer which protects us from harmful, ultraviolet rays of the sun., , Refer page 205-206., Washing away of pesticides and chemical fertilisers with, water into nearby water sources cause water pollution., This is mainly due to pollution and excessive use by the, increasing population, industrialisation and our unfriendly, attitude towards our environment.

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GURUKUL CENTRAL ACADMY, 7., , 8., , F., , Thermal power plants release hot water into the natural, water sources. The change in temperature decreases the, oxygen content of the water. Other industries such as oil, refineries, paper factories, chemical factories, sugar and, textile mills, release chemicals such as arsenic, lead and, fluorides into water bodies causing chemical contamination, of water., RO purifiers are based on the concept of Reverse Osmosis., Water is passed through a semipermeable membrane to, remove impurities., , 1. Refer page 203., 2., , 3., , The rain water containing dissolved acids is called acid, rain. Power plants release the majority of sulphur dioxide., Nitrogen oxides are released when fossil fuels, such as coal, is burnt to produce electricity. In addition, the exhaust from, cars, trucks, and buses also releases these chemicals into the, air. All these pollutants cause acid rain. The acid corrodes, metallic structures such as bridges and railway tracks. It, also makes water sources acidic., Trapping of solar radiations due to the presence of, greenhouse gases is called greenhouse effect., , Refer Fig. 18.2.

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GURUKUL CENTRAL ACADMY, 4., , 5., , 6., , 7., , Soil particles, plant spores, processing of minerals are the, sources of dust particles in air. Smoke combines with other, air pollutants and fog to form smog causing asthma, cough, and wheezing in children., The air pollutants released by vehicles and chemical, industries cause many diseases such as, asthma, bronchitis,, cancer, chest pain, coughing and allergies., Fossil fuels burn and release carbon monoxide. It easily, mixes with haemoglobin and disturbs the transport of, oxygen by the red blood cells in the body. Due to this,, dizziness, nausea and headache may occur., Air pollution also causes harmful effects on the growth and, functioning of plants. Dust particles of cement deposit on, leaves causing chlorosis or yellowing of leaves., Fossil fuels like petrol, diesel, kerosene and coal, when, burnt release many poisonous gases. Vehicles like cars,, buses, trucks, scooters, motorcycles, etc., release smoke and, harmful gases in the air due to burning of fuels. These are, the major causes of air pollution., , Refer page 205., Potable water is water which is fit for consumption by, humans and animals. It is also called drinking water. It must, have all the following characteristics:, • Potable water should be clean, transparent, colourless,, tasteless and odourless., • It should not contain any harmful chemicals. germs and, , © Vishv Books, Ph. +91-0120-4698888; www.vishvbook.com, , 80, , 1901/5

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GURUKUL CENTRAL ACADMY, impurities., • Potable, water must contain sufficient quantity of, dissolved oxygen and salts., • A water sample which may odourless, colourless and, clear may not necessarily be potable. It may contain, dissolved impurities and disease causing germs., 8., , At homes, water can be purified by physical or chemical, means. The three common methods used to purify water, are: Boiling: Boiling water is the simplest way of purifying, water. Water is boiled for 15–20 minutes and then cooled., This kills germs present in it., Filtration: Different types of filters and purifiers are used., In the traditional sand filters, water was passed through, gravel, sand and charcoal layers to obtain clean water., Nowadays hassle-free filters and purifiers are used in, households and offices. RO purifiers are based on the, concept of Reverse Osmosis. Water is passed through a, semipermeable membrane to remove impurities., Using chemicals: Chemicals such as chlorine tablets or, potassium permanganate are added to kill germs.