1) If the diameter of a sewer is 100 mm, the gradient required for generating self cleansing velocity is__________________? a. 1 in 60 b. 1 in 100 c. 1 in 120 d. None of these
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2) In 1000 kg of sewage, the total solids approximate___________________? a. 0.5 to 1.0 kg b. 1 kg to 2.0 kg c. 5 kg to 7.5 kg d. 7.5 kg to 10 kg
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3) Before discharging the foul sewage into rivers, it is generally treated by_____________________? a. Screening b. Sedimentation c. Oxidation d. All the above
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4) Aerobic activity is maximum_______________? a. In freshly produced sewage b. At sewer pipes c. In sewer treatment plants d. None of these
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5) Sewer manholes are generally provided at________________? a. The change of gradient b. The change of direction c. The junctions of sewers d. All of these
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6) hydraulically equivalent, the relationship which holds good, is _______________? a. D8/3 = 4 b8/3 b. D3/8 = 4 b3/8 c. D2/3 = 4 b2/3 d. D3/2 = 4 b3/2
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7) Sewer pipes need be checked for_________________? a. Minimum flow b. Maximum flow c. Both A. and B. d. None of these
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8) In septic tanks, decomposition of organic bacteria, is done by_____________________? a. Anaerobic bacteria b. Aerobic bacteria c. Both types of bacterias d. None of these
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9) The sewerage system originates from__________________? a. House sewers b. Lateral sewers c. Branch sewers d. Main sewers
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10) During purification process of sewage the gas given off, is________________? a. Carbon dioxide b. Hydrogen c. Ammonia d. All the above
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11) Drop manholes at the junctions of sewer lines, are provided if________________? a. Invert level of a branch sewer is more than 60 cm that of the main sewer b. Sewer line runs along a main road c. Ordinary manhole cannot be built d. Two sewer lines intersect
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12) The sewage discharge in a detritus tank of a treatment plant is 576 litres/sec with flow velocity of 0.2 m/sec. If the ratio of width to depth is 2, the depth is____________________? a. 100 cm b. 110 cm c. 120 cm d. 150 cm
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13) Fresh sewage may become stale in_________________? a. One hour b. Two to three hours c. Three to four hours d. Six hours
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14) The standard B.O.D. of water is taken for_________________? a. 1 day b. 2 days c. 3 days d. 5 days
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15) The gradient of sewers depends upon_________________? a. Velocity of flow b. Diameter of the sewer c. Discharge d. All the above
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16) Removal of oil and grease from sewage, is known____________________? a. Screening b. Skimming c. Filtration d. None of these
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17) The ratio of minimum hourly flow to the average flow of sewage is_________________? a. 1/4 b. 1/3 c. 1/2 d. 3/4
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18) The coagulant widely used for sewage treatment, is_________________? a. Alum b. Ferric chloride c. Ferric sulphate d. Chlorinated copperas
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19) For the survival of fish in a river stream, the minimum dissolved oxygen is prescribed________________? a. 3 ppm b. 4 ppm c. 5 ppm d. 10 ppm
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20) In SI units the power of sound is represented in __________________? a. Kgs b. Joules c. Newtons d. Watts
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