civil engineering MCQs – Page 98

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 Review each marked answer and report any item that may be outdated or unclear.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
4851. For drainage pipes in buildings the test applied before putting them to use, is__________________?
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A. Water test

B. Straightness test

C. Smoke test

D. All the above

4852. The pressure exerted by_____________?
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A. Pressure sewers are designed to be safe in tension

B. All the above

C. The internal pressure if any, causes tensile stress in the pipe material

D. The sewage when running full from inside, is called internal pressure

4853. Acid regression stage of sludge digestion at a temperature 21C extends over a period of______________?
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A. 30 days

B. 90 days

C. 60 days

D. 15 days

4854. Hydraulic mean radius is_______________?
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A. Mean of radii in a pipe line of varying cross -sections

B. Mean radius of sewer

C. Difference in heads between two points in circular pipes

D. Cross-sectional area/wetted perimeter
4855. The asbestos cement sewers are_________________?
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A. Susceptible to corrosion by sulphuric acid

B. Not structurally strong to bear large compressive stress

C. Light in weight

D. All the above
4856. For a continuous flow type of sedimentation tanks__________________?
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A. Length of the tank is normally kept 4 to 5 times the width

B. Width of the tank is normally kept about 6 m

C. Maximum horizontal flow velocity is limited to 0.3 m/minute

D. All the above
4857. For treating the sewage of a large city, you will recommend_________________?
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A. Sedimentation tanks with high rate trickling filters

B. A plant consisting of Imhoff tanks with low rate trickling filters

C. None of these

D. A sedimentation tank and an activated sludge treatment plant
4858. The sewer which received discharge from two or more main sewers, is known as_______________?
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A. A trunk sewer

B. A main sewer

C. An intercepting sewer

D. An outfall sewer

4859. The drainage area of a town is 12 hectares. Its 40% area is hard pavement ( K = 0.85), the 40% area is unpaved streets (K = 0.20) and the remaining is wooded areas (K = 0.15). Assuming the time of concentration for the areas as 30 minutes and using the formula Ps = 900/(t + 60) the maximum run off is__________________?
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A. 0.10 cumec

B. 0.12 cumec

C. 0.15 cumec

D. 0.20 cumec

4860. R.M.O. expenses include___________________?
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A. Running expenses

B. Maintenance expenses

C. All the above

D. Operation expenses

4861. No treatment of the sewage is given if dilution factor is_____________?
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A. More than 500

B. Less than 150

C. Between 200 to 300

D. Between 150 to 200

4862. th or th extra space is left in sewer pipes at maximum discharge for_________________?
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A. Unexpected increase in population

B. Low estimates of the average and maximum flows

C. Large scale infiltration of storm water

D. All the above
4863. The rational formula for peak drainage discharge, was evolved by_________________?
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A. Fruhling

B. Kuichling

C. All of these

D. Lloyd David

4864. The rainfall at any place may be determined by__________________?
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A. Its intensity

B. All the above

C. Its direction

D. Its frequency

4865. The coagulant which is generally not used for treating the sewage, is__________________?
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A. Ferric chloride

B. Ferric sulphate

C. Chlorinated copperas

D. Alum
4866. Bottom openings 15 cm 15 cm in the standing baffle wall are provided________________?
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A. 22.5 cm c/c

B. 15 cm c/c

C. 50 cm c/c

D. 30 cm c/c

4867. If the flame of a miners safety lamp in the upper layers of the sewer forms an explosive, the sewer certainly contains_______________?
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A. Methane

B. Hydrogen sulphide

C. Carbon dioxide

D. Oxygen

4868. The Chezys constant C in the formula V = C_________________?
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A. Shape of the sewer

B. Roughness of sewer surface

C. Size of the sewer

D. All the above
4869. Pick up the correct statement from the following ?
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A. Rate of digestion of sludge is more at higher temperature

B. Thermophilic organisms digest the sludge if the temperature ranges from 40 to 60C

C. Mesophilic organisms digest the sludge if the temperature is between 25 and 40C

D. All the above
4870. Traps_________________?
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A. Dissolve the foul gases

B. Create symphonic action to increase the quick disposal of sewerage

C. Are used to trap the rats entering sewers

D. Are water seals which prevent the entry of foul gases
4871. 1000 kg of sewage contains________________?
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A. 0.112 kg in suspension

B. 0.112 kg in solution

C. 0.225 kg in solution

D. Both A. and C. of above
4872. For efficient working of a sewer, it must be ensured that _____________?
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A. Minimum velocity of 0.45 m/sec, is maintained at its minimum flow

B. A maximum velocity of 0.90 m/sec, is maintained at its maximum flow

C. Both A. and B.

D. Neither A. nor B.

4873. Assertion A.: The determination of pH value of sewerage is important. Reason (R): The efficiency of certain treatment methods depends upon the availability of pH value________________?
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A. Both A and R are true and R is the correct explanation of A

B. Both A and R are true but R is not a correct explanation of A

C. A is true but R is false

D. A is false but R is true

4874. Aerobic bacterias___________________?
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A. Consume organic matter as their food

B. Oxidise organic matter in sewage

C. All the above

D. Flourish in the presence of free oxygen

4875. For the open drain (N = 0.025) shown in the below figure, the discharge is________________?
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A. 28.88 cumecs

B. 29.88 cumecs

C. 26.88 cumecs

D. 27.88 cumecs

4876. Pick up the correct statement from the following ?
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A. All the above

B. The sewer pipes of sizes greater than 0.4 m diameter are designed as running 2/3rd or 3/4th full at maximum discharge

C. The minimum design velocity of sewer pipes is taken as 0.8 m/sec

D. The sewer pipes of sizes less than 0.4 m diameter are designed as running full at maximum discharge

4877. The sludge does not contain waste water from_________________?
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A. Wash basins

B. Bath rooms

C. Toilets

D. Kitchen sinks

4878. The porosity of sediments in sewer pipes, is usually taken as___________________?
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A. 0.01

B. 0.011

C. 0.013

D. 0.012

4879. For detecting the nitrates in sewage, the colour may be developed by adding________________?
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A. None of these

B. Potassium permanganate

C. Phenol-di -sulphuric acid and potassium hydroxide

D. Sulphuric acid and napthamine

4880. For house drainage minimum gradient is__________________?
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A. 1 in 60

B. 1 in 80

C. 1 in 10

D. 1 in 400

4881. 15 cumecs, the depth d and width are related by For drains up to___________________?
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A. B = 0.5 d

B. d = 0.2 B

C. B = 0.2 d

D. d = 0.5 B
4882. The density of population over 40 hectares is 250/hectare. If water supply demand per day is 200 litres and sewage discharge is 80% of water supply, the sewage flow in sewers of separate system, is_____________________?
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A. 0.05556 cumec

B. 0.05554 cumec

C. 0.0556 cumec

D. 0.05552 cumec

4883. In trickling filter, B.O.D. is reduced to___________________?
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A. 40 to 60%

B. 30 to 40%

C. 60 to 80%

D. 80 to 90%

4884. The coagulant widely used for sewage treatment, is_________________?
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A. Ferric sulphate

B. Ferric chloride

C. Chlorinated copperas

D. Alum

4885. The rate of accumulation of sludge in septic tanks is recommended as____________________?
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A. 25 litres/person/year

B. 30 litres/person/month

C. 30 litres/person/year

D. 25 litres/person/month

4886. The maximum diameter of sewers adopted in the designs is_______________?
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A. 4.0 m

B. 2.0 m

C. 1.0 m

D. 3.0 m
4887. For laying a sewer line in a trench of 2 m width, an offset line is marked on the ground parallel to the given centre line at a distance of___________________?
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A. 160 cm

B. 140 cm

C. 100 cm

D. 120 cm

4888. Before discharging the foul sewage into rivers, it is generally treated by_____________________?
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A. All the above

B. Screening

C. Sedimentation

D. Oxidation

4889. For sewers, inverted siphon is provided for___________________?
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A. One pipe

B. Three pipes

C. Two pipes

D. Four pipes

4890. If the diameter of sewer is 225 mm, the gradient required for generating self cleansing velocity, is___________________?
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A. 1 in 100

B. 1 in 60

C. None of these

D. 1 in 120
4891. The flow velocity in detritus tanks is________________?
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A. 0.05 m/sec

B. 0.09 m/sec

C. None of these

D. 1.25 m/sec

4892. The ratio of maximum sewage flow to average sewage flow for mains up to 1 m in diameter, is___________________?
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A. 2.0

B. 1.5

C. 4

D. 3

4893. For evaporation and measurement of settable solids, the apparatus used, is________________?
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A. A test tube

B. A breaker

C. A jar

D. An Imhoff cone
4894. The sewer pipes__________________?
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A. All the above

B. Are designed for generating self-cleansing velocities at different discharge

C. Carry sewage as gravity conduits

D. Should resist the wear and tear caused due to abrasion

4895. The most effective arrangement for diverting excess storm water into a natural drainage, is____________________?
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A. None of these

B. Overflow weir

C. Leaping weir

D. Siphon spill way
4896. Removal of oil and grease from sewage, is known____________________?
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A. Screening

B. None of these

C. Filtration

D. Skimming
4897. Assertion A.: The minimum self cleansing velocity in the sewer, at least once a day, must be generated. Reason (R): If certain deposition takes place and is not removed, it obstructs free flow and causes further deposition leading to complete blocking of the sewer?
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A. Both A and R are true and R is the correct explanation of A

B. Both A and R are true but R is not a correct explanation of A

C. A is true but R is false

D. A is false but R is true

4898. In very first stage of decomposition of the organic matter in sewage________________?
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A. Nitrites are formed

B. Nitrates are formed

C. Ammonia is formed

D. Carbondioxide is formed

4899. Pathogens (or pathogenic bacterias) in water may cause___________________?
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A. Dysentery

B. Typhoid

C. Cholera

D. All the above
4900. A nuisance is experienced in diluting water if dilution factor is less than_________________?
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A. 60

B. 40

C. 20

D. 100