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1) A sewer that receives the discharge of a number of house sewers is called________________? a. house sewer b. lateral sewer c. intercepting sewer d. submain sewer
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2) The type of valve which allows water to flow in one direction but prevents its flow in the reverse direction is____________________? a. reflux valve b. sluice valve c. air relief valve d. pressure relief valve
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3) Hardy cross method of analysis of distribution system________________?
1) involves successive trials 2) takes economic aspects into account 3) is time consuming The correct answer is? a. only (1) b. (1)and(2) c. (1) and (3) d. all are correct
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4) Which of the following methods of analysis of water distribution system is most suitable for long and narrow pipe system ? a. circle method b. equivalent pipe method c. Hardy cross method d. electrical analysis method
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5) The layout of distribution system in which water flows towards the outer periphery is_________________? a. ring system b. dead end system c. radial system d. grid iron system
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6) As compared to cast iron pipes, steel pipes are______________? a. heavier b. stronger c. costlier d. less susceptible to corrosion
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7) Which of the following compounds is widely used for algae control ? a. sodium sulphate b. copper sulphate c. sodium chloride d. calcium chloride
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8) In lime-soda process________________? a. only carbonate hardness is removed b. only non-carbonate hardness is re-moved c. lime reduces the carbonate hardness and soda-ash removes the non-carbo¬nate hardness d. lime reduces the non-carbonate hard-ness and soda-ash removes the carbo¬nate hardness
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9) As compared to higher pH values, the contact period required for efficient chlorination at lower pH values is___________________? a. smaller b. larger c. same d. none of the above
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10) Which of the following chemical compounds can be used for dechlorination of water ? a. carbon dioxide b. bleaching powder c. sulphur dioxide d. chloramines
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11) The treatment of water with bleaching powder is known as________________? a. prechlorination b. super chlorination c. dechlorination d. hypochlorination
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12) The process in which the chlorination is done beyond the break point is known as_________________? a. prechlorination b. post chlorination c. super chlorination d. break point chlorination
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13) The disinfection efficiency of chlorine increases by_______________?
1) decreasing the time of contact 2) decreasing the temperature of water 3) increasing the temperature of water The correct answer is ? a. only (1) b. both (1) and (2) c. both (1) and (3) d. only (3)
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14) Double filtration is used_______________? a. to increase the filtration slow sand filters capacity of b. to increase the filtration rapid sand filters capacity of c. for isolated buildings like pools, hotels etc swimming d. all of the above
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15) Disinfection of water results in______________? a. removal of turbidity b. removal of hardness c. killing of disease bacteria d. complete sterilisation
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16) Period of cleaning of slow sand filters is about________________? a. 24 – 48 hours b. 10-12 days c. 2-3 months d. 1-2 year
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17) Cleaning is done by________________?
1) scraping and removal in filters slow sand 2) back washing in slow sand filters 3) scraping and removal in filters rapid sand 4) back washing in rapid sand filters The correct answer is a. (1) and (2) b. (2) and (3) c. (1) and (4) d. (2) and (4)
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18) Air binding phenomena in rapid sand filters occur due to_________________? a. excessive negative head b. mud ball formation c. higher turbidity in the effluent d. low temperature
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19) As compared to rapid sand filters, slow sand filters give______________?
1) slower filtration rate 2) higher filtration rate 3) lesser efficiency in removal of bacteria 4) higher efficiency in removal of bacteria The correct answer is? a. (1) and (2) b. (2) and (3) c. (1) and (4) d. (2) and (4)
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20) The rate of filtration in slow sand filters in million litres per day per hectare is about_____________? a. 50 to 60 b. 100 to 150 c. 500 to 600 d. 1400 to 1500
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