civil engineering MCQs – Page 249

Practise multiple-choice questions from civil engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

civil engineering Mcqs
4961. Dried sewage after treatment is used as____________________?
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A. Chemical for lowering B.O.D.

B. Fertilizer

C. Base material for paints

D. Building material

4962. 5 days-biochemical oxygen demand (BOD5) is taken at a temperature of_________________?
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A. 15C

B. 0C

C. 20C

D. 25C

4963. Pick up the incorrect statement from the following ?
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A. Septic tanks are generally provided a detention period of 12 to 36 hours

B. Septic tanks are completely covered and high vent shafts are provided for the escape of foul gases

C. None of these

D. Septic tanks are horizontal continuous flow type of sedimentation tanks

4964. Flocculated particles do not change their___________________?
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A. Weight

B. Size

C. None of these

D. Shape

4965. The sewerage system originates from__________________?
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A. House sewers

B. Lateral sewers

C. Main sewers

D. Branch sewers

4966. Pick up the correct statement from the following _________________?
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A. The screenings are disposed off either by burning or by burial or by dumping

B. All the above

C. The materials separated by screens, is called screenings

D. The process of burning the screenings, is known as compositing

4967. The design period of sewage treatment works in normally_________________?
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A. 30 40 years

B. 5 10 years

C. 15 20 years

D. 40 50 years

4968. If the depletion of oxygen is found to be 2.5 mg/litre after incubating 2.5 ml of sewage diluted to 250 ml for 5 days at 20C, B.O.D. of the sewage is_________________?
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A. 250 mg/l

B. 150 mg/l

C. 50 mg/l

D. 100 mg/l

4969. An inverted siphon is designed generally for____________________?
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A. Three pipes

B. One pipe

C. Two pipes

D. Four pipes

4970. The detention time of a circular tank of diameter d and water depth H, for receiving the sewage Q per hour, is________________?
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A. d (0.285d + 0.011H)/Q

B. d (0.011d + 0.785H)/Q

C. d (0.022d + 0.085H)/Q

D. d (0.785d + 0.011H)/Q

4971. For detecting the nitrites in the sewage, the matching colour may be developed by adding_________________?
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A. None of these

B. Potassium permanganate

C. Sulphuric acid and napthamine

D. Phenol-di -sulphuric acid potassium hydroxide

4972. In case of Imhoff tanks_____________________?
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A. Detention period is 2 hours

B. The velocity of flow is restricted to 0.30 m/minute

C. The shape is rectangular

D. All the above
4973. running partially full with central angle , For a circular sewer of diameter__________________?
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A. r/R = [1

B. d/D = (1

C. a/A

D. All the above
4974. Chlorination of water is done for the removal of____________________?
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A. Hardness

B. Sediments

C. Suspended solids

D. Bacterias
4975. For design purposes, the normal rate of infiltration of ground water into the sewer, is___________________?
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A. 1500 litres/km/cm

B. 1000 litres/km/cm

C. 2000 litres/km/cm

D. 500 litres/km/cm

4976. The liquid wastes from kitchens, bath rooms and wash basins, is not called________________?
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A. Sullage

B. Sewage

C. None of these

D. Liquid waste

4977. For the survival of fish in a river stream, the minimum dissolved oxygen is prescribed________________?
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A. 4 ppm

B. 3 ppm

C. 5 ppm

D. 10 ppm

4978. Lead caulked joints are used for laying____________________?
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A. G.I. pipes

B. Stone ware pipes

C. Earthenware pipes

D. C.I. pipes

4979. It is customary to design a sewer for D.W.F. on the basis of________________?
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A. Four times the average demand

B. Average demand

C. Twice the average demand

D. Thrice the average demand
4980. The dimensions of a rectangular settling tank are: length 24 m, width 6 m and depth 3 m. If 2 hour detention period for tanks is recommended, the rate of flow of sewage per hour, is_____________________?
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A. 216 cu.m

B. 212 cu.m

C. 204 cu.m

D. 208 cu.m