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1) In sewage treatment plants, large material is removed by a. metal screen b. grit tank c. sludge tank d. filter bed
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2) Desalination plants are used to convert a. hot water to cold water b. cold water to hot water c. tasteless water to salty water d. salty water to tasteless water
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3) The population which does not have tap water in their homes, is a. two-third of the world population b. one-third of the world population c. half of the world population d. quarter of the world population
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4) Water can be kept clean by detergents, if they are a. not poisonous b. odorless c. biodegradable d. non biodegradable
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5) 'Distillation' can also be used to treat a. fresh water b. sewage water c. polluted water d. rain water
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6) As the water evaporates, due to cold air it a. drops back b. condenses c. turns into liquid d. turns in gas
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7) Hot water is bad for fish eggs to a. lay b. mature c. hatch d. grow
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8) At treatment plant, raw water is mixed with alum and lime, it is called a. coagulation b. sedimentation c. filtration d. chlorination
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9) The average amount of water which a large deciduous tree takes, is a. 1000 liters b. 20,000 liters c. 5000 liters d. 50,000 liters
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10) The water in ponds, lakes, streams and rivers is called fresh water because it is a. sweet b. tasteless c. bitter d. clean
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11) A method which is used to obtain fresh water, is a. chlorination b. filtration c. distillation d. zinc
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12) The parasite worms spend a part of their life in a. human stomach b. human intestines c. human blood vessels d. human liver
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13) One-third of the water consumption by humans, goes to a. drinking water b. flushing toilets c. bathing d. washing cooking utensils
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14) Distilled water contains a. poison b. bacteria c. minerals d. pure water without minerals
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15) An artificial lake made by building a dam across river is called a a. pond b. reservoir c. lake d. stream
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16) The bacteria that decompose algae take up all the a. sunlight b. oxygen c. minerals d. useful gases in the water
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17) 'Water' is a. sweet b. sour c. bitter d. odorless
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18) As compared to shower, the bath tub uses a. less water b. more water c. equal water d. not sure
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19) Human feces stimulates the growth of a. algae b. fungi c. bacteria d. viruses
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20) The crops that need a lot of water are a. rice and maize b. wheat and maize c. rice and wheat d. maize and other grains
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