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1) The means of access for inspection and cleaning of sewer line is known as_______________? a. inlet b. manhole c. drop manhole d. catch basin
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2) Dissolved oxygen in streams is______________? a. maximum at noon b. minimum at noon c. maximum at midnight d. same throughout the day
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3) The minimum dissolved oxygen which should always be present in water in order to save the aquatic life is______________? a. 1 ppm b. 4 ppm c. 10 ppm d. 40 ppm
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4) The ratio of 5 day BOD to ultimate BOD is about_______________? a. 1/3 b. 2/3 c. 3/4 d. 1.0
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5) The correct relation between theoretical oxygen demand (TOD), Biochemical oxygen demand (BOD) and Chemical oxygen demand (COD) is given by_______________? a. TOD>BOD>COD b. TOD>COD>BOD c. BOD>COD>TOD d. COD>BOD>TOD
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6) Settling velocity increases with_______________? a. specific gravity of solid particles b. size of particles c. depth of tank d. temperature of liquid
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7) Which of the following retards the self purification of stream ? a. higher temperature b. sunlight c. satisfying oxygen demand d. none of the above
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8) The characteristics of fresh and septic sewage respectively are____________________? a. acidic and alkaline b. alkaline and acidic c. both acidic d. both alkaline
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9) The most commonly used sewer under culverts is_______________? a. circular brick sewer b. circular cast iron sewer c. semi-elliptical sewer d. horse-shoe type sewer
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10) An egg shaped section of sewer________________? a. is economical than circular section b. provides self cleansing velocity at low discharges c. is more stable than circular section d. is easy to construct
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11) The main disadvantage of cement concrete sewers is________________? a. less strength b. difficulty in construction c. difficulty in transportation due to heavy weight d. less life
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12) The design discharge for the combined sewer system shall be taken as________________? a. equal to rainfall b. rainfall + DWF c. rainfall + 2 DWF d. rainfall + 6 DWF
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13) The slope of sewer shall be__________________? a. given in the direction of natural slope of ground b. given in the direction opposite to natural slope of ground c. zero d. steeper than 1 in 20
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14) The specific gravity of sewage is_______________? a. much greater than 1 b. slightly less than 1 c. equal to 1 d. slightly greater than 1
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15) If the time of concentration is 9 minutes, then the intensity of rainfall according to British Ministry of Health formula will be__________________? a. 4 mm/hr b. 10mm/hr c. 20 mm/hr d. 40 mm/hr
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16) The suitable system of sanitation for area of distributed rainfall throughout the year with less intensity is_________________? a. separate system b. combined system c. partially separate system d. partially combined system
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17) Sewerage system is usually designed for_________________? a. 10 years b. 25 years c. 50 years d. 75 years
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18) The hydraulic mean depth (HMD. for an egg-shaped sewer flowing two-third full is_______________? a. equal to HMD when flowing full b. less than HMD when flowing full c. greater than HMD when flowing full d. none of the above
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19) If Biochemical oxygen demand (BOD. of a town is 20000 kg/day and BOD per capita per day is 0.05 kg, then population equivalent of town is_________________? a. 1000 b. 4000 c. 100000 d. 400000
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20) For a country like India, where rainfall is mainly confined to one season, the suitable sewerage system will be________________? a. separate system b. combined system c. partially combined system d. partially separate system
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