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GURUKUL CENTRAL ACADMY, CH- 16- AIR AROUND US, WORKSHEET-1, A. 1. Oxygen is used for both respiration and combustion., 2. Air has mass., 3. Plants release oxygen during photosynthesis., 4. Moving air helps generate energy ., 5. Air contains water vapour. B, C, D Refer to, book WORKSHEET-2, A. Clue— uncontrollable burning and its effects, B. Clue— Air inflates the objects, 1. prevents major head injuries if the vehicle collides, 2. prevents the wearer from drowning, 3. makes it easier to play with, 4. helps it rise, To generate electricity, grind grains and draw water., , EXERCISES, A., , 1. d. 2. c. 3. b. 4. b. 5. b. 6. a. 7. C, , B., , 1. True, 2. True, 3. False; Respiration and combustion produce carbon dioxide in the, air., 4. True, 5. False; Soil contains air.

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GURUKUL CENTRAL ACADMY, C., , 1. soil, 2. oxygen, 3. mixture, 3. Oxygen 6. atmosphere 7. Brakes, , 4. 78, , D., , 1. Oxygen, 2. Atmosphere, 3. Power, 4. Carbon dioxide, 5. Ultraviolet radiation, 6. Oxygen, 7. Air pollution, , E., , 1. Nitrogen (78%) and oxygen (21%). Other gases (1%) present, include carbon dioxide (0.03%), argon, neon, helium, etc., 2. Because, , the air gets thinner and the oxygen level in the air decreases, as we go higher on the mountains., , 3. Air, , is trapped in the spaces between the soil particles. It is, displaced when water enters these spaces and forms bubbles., , 4. Refer, , Activity 6, page 175., , 5. Fine, , hair and mucus in our nostrils act as filters and prevent the, entry of dust particles in our respiratory system., , 6., , a. Respiration: The process in which breaking down of food, takes place to release energy, carbon dioxide and water vapour is, called respiration., Breathing: The process in which we inhale oxygen and exhale, carbon dioxide is called breathing.

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GURUKUL CENTRAL ACADMY, b. Air: Mixture of gases like nitrogen, oxygen, carbon dioxide, and many other gases., Wind: Moving air is called wind., 7. To maintain, , F., , oxygen and carbon dioxide cycle., , 1. Refer Activity 2, page 173., 2., , • Clouds move with the wind. This way the wind helps, bring rain to different places., • Wind helps in the dispersal of seeds and pollen grains., • The wind helps in the winnowing of foodgrains., • Wind guides the movement of parachutes, gliders,, aeroplanes and sailboats., • Wind is used to run windmills. Windmill is a machine that turns, in the wind and generates power to do mechanical work and to, generate electricity., , 3., , Refer page 176., , 4., , The atmosphere also helps to maintain the right temperature on, the earth. The light and heat of the sun falls on the earth’s, atmosphere. Some of it is absorbed by the atmosphere, while the, rest is reflected back. This prevents the earth from becoming very, hot during the day. At night, the trapped heat in the atmosphere, prevents the earth from cooling down too much. Thus,, atmosphere helps to keep the earth’s surface at the right, temperature for the life to exist., , 5., , When unwanted particles and gases mix with air, it is called air, pollution. Burning of fuels, smoke from chimneys and vehicles