civil engineering MCQs – Page 100

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 Review each marked answer and report any item that may be outdated or unclear.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
4951. The recommended detention period for grit chambers is_______________?
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A. 1 minute

B. 3 minutes

C. 5 minutes

D. 2 minutes

4952. The sewer which collects the discharge from a collecting system and delivers it to a treatment plant, is known_____________________?
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A. Branch sewer

B. Sewer outfall

C. House sewer

D. Lateral sewer

4953. If the diameter of a sewer is 100 mm, the gradient required for generating self cleansing velocity is__________________?
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A. None of these

B. 1 in 120

C. 1 in 60

D. 1 in 100

4954. In a trickling filter_________________?
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A. Filtration process is used

B. Biological action is used

C. Neither A. nor B.

D. Both A. and B.

4955. The gradient of sewers depends upon_________________?
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A. All the above

B. Discharge

C. Velocity of flow

D. Diameter of the sewer

4956. In a fully mechanised composting plant, involves________________?
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A. Mechanized receipt

B. All of these

C. Mechanized segregation

D. Mechanized pulverising of refuse

4957. The clarigesters are_________________?
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A. Circular Imhoff double tanks with bottom hoppers

B. Circular septic tanks

C. Circular Imhoff double storey tanks without bottom hoppers

D. Rectangular septic tanks

4958. If is the diameter of upper circular portion, the overall depth of New Egg shaped sewer section, Is_____________________?
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A. 1.425 D

B. 1.625 D

C. 1.250 D

D. 1.350 D

4959. Pick up the correct statement from the following ?
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A. Medium sewers are cleaned by cane rodding

B. Small sewers are cleaned by flushing

C. All the above

D. Medium sewers may be cleaned by pills

4960. Pick up the correct statement from the following?
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A. The period after which the entire area starts contributing to the runoff, is called the time of concentration

B. All the above

C. The maximum rate of storm runoff is called peak drainage discharge

D. Rational method of estimating peak run off, may be used precisely for areas less than 50 hectares

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

4981. Ventilating shafts are provided to a sewer line at every__________________?
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A. 150 m

B. 100 m

C. 200 m

D. 300 m
4982. A sewer running partially full and hurried with back filled, fails in compression due to_________________?
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A. Weight of the back fill

B. All the above

C. Weight of the pipe

D. Superimposed traffic loads

4983. In a residential colony, sewers of diameters 100 mm, 150 mm and 225 mm were laid with a gradient 1 in 120. Which portion of the sewage system does not choke in due course of time?
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A. All of these

B. 225 mm dia.

C. 100 mm dia.

D. 150 mm dia.

4984. Hazens formula VS = 418 (GS Gw)d [(3T + 70)/100] is used for the settlement velocity of the particles of diameter______________________?
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A. Greater than 0.1 mm

B. Less than 0.01 mm

C. Less than 0.05 mm

D. Less than 0.1 mm

4985. Nitrogen cycle of sewage, is____________________?
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A. Liberation of nitrogen-formation of nitrates-formation of nitrites-liberation of ammonia

B. Liberation of nitrogen-liberation of ammonia-formation of nitrites- formation of nitrates

C. Liberation of ammonia-formation of nitrites-formation of nitrates-liberation of nitrogen

D. Formation of nitrates-formation of nitrites-liberation of nitrates-liberation of nitrates

4986. A rainfall may be classified as acidic if its pH value is less or equal to________________?
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A. 6

B. 6.5

C. 7

D. 5
4987. Which one of the following statements regarding septic tanks is wrong ?
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A. The depth of tank is kept equal to its width

B. The outlet invert level is kept 5 to 7.5 cm below the inlet invert level

C. A gap of 7.5 cm between the bottom of the covering slab and the top level of scum is provided

D. The minimum width of septic level is 90 cm

4988. The most dangerous pollutant in vehicular emissions is____________________?
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A. O3

B. CO2

C. SO2

D. CO
4989. If the pH value of sewage is 7__________________?
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A. It is neutral

B. It is alkaline

C. It is acidic

D. None of these

4990. pH value of sludge during alkaline regression stage, is__________________?
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A. More than 6

B. Less than 6

C. Less than 7

D. More than 7
4991. 3.0 ml of raw sewage is diluted to 300 ml. The D.O. concentration of the diluted sample at the beginning of the test was 8 mg/l. After 5 day-incubation at 20C, the D.O. concentration was 5 mg/l. The BOD of raw sewerage is______________________?
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A. 300 mg/l

B. 400 mg/l

C. 200 mg/l

D. 100 mg/l

4992. The gas evolved in sewers is________________?
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A. Carbondioxide

B. Hydrogen sulphide

C. Methane

D. All of these
4993. If D is the diameter of a circular sewer and D is the top horizontal diameter of an equivalent egg shaped section, the relationship which holds good, is_______________?
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A. D = 0.94 D

B. D = 0.74 D

C. D = 0.64 D

D. D = 0.84 D
4994. The screens are fixed___________________?
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A. Parallel to the direction of flow

B. None of these

C. Perpendicular to the direction of flow

D. At an angle 30 to 60 to the direction of flow
4995. House connections to the laterals is generally made by___________________?
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A. Glazed stonewares

B. Cast iron

C. R.C.C.

D. P.C.C.

4996. Skimming tanks are__________________?
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A. Tanks provided with self- cleansing screens

B. Improved version of grit chambers

C. Used to remove the grease and oil

D. Those from which sludge is skimmed out

4997. If the side of a square sewer is 1000 mm, the diameter of a hydraulically equivalent circular section, is___________________?
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A. 1065 mm

B. 1095 mm

C. 1075 mm

D. 1045 mm

4998. The sewerage system consists of______________________?
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A. All of these

B. Branch sewer

C. House sewer

D. Lateral sewer

4999. The disintegrating pump in which solid matter is broken up before passing out, is__________________?
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A. Pneumatic ejector

B. None of these

C. Reciprocating pump

D. Centrifugal pump
5000. In sewers the gas generally found, is_________________?
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A. All the above

B. Hydrogen sulphide (H2S)

C. Carbon dioxide (CO2)

D. Methane (CH4)