civil engineering Mcqs
4901. 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

4902. Disposal to sewage in large cities, is done in__________________?
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A. Purification

B. Dilution

C. Irrigation

D. Oxidation

4903. The spacing of bars of perforations of fine screens used for the treatment of sewage, is_______________?
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A. 2 to 3 mm

B. 3 to 5 mm

C. 8 to 10 mm

D. 5 to 8 mm

4904. The ratio of minimum hourly flow to the average flow of sewage is_________________?
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A. 2-Jan

B. 4-Jan

C. 4-Mar

D. 1/3
4905. In a sludge tank, the gas mainly produced, is_________________?
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A. Oxygen

B. Nitrogen

C. Hydrogen

D. Carbon dioxide
4906. The non-clog pump which permits solid matter to pass out with the liquid sewage, is________________?
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A. Centrifugal pump

B. None of these

C. Reciprocating pump

D. Pneumatic ejector

4907. The algae dies out in the zone of_____________________?
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A. Degradation

B. Cleaner water

C. Active decomposition

D. Recovery

4908. A manhole is generally provided at each__________________?
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A. Change of gradient

B. Junction

C. All the above

D. Bend

4909. The sewers___________________?
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A. Must be of adequate size to avoid over flow

B. Must flow under gravity to full

C. Must be laid at least 2 to 3 m deep to collect /water from the basements

D. All the above
4910. Cowl is provided at___________________?
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A. Lower end of ventilating column

B. Upper end of the manhole

C. First step in manhole

D. Upper end of ventilating column
4911. With self cleansing velocity in sewers___________________?
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A. Silting occurs at bottom

B. Scouring occurs at bottom

C. Both silting and scouring occur at bottom

D. Neither silting nor scouring occurs at bottom
4912. In olden days the type of section adopted in trunk and out fall sewers was__________________?
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A. Horse shoe shaped

B. Parabolic shaped

C. Egg shaped

D. Circular shaped

4913. Design period of 40 to 50 years is adopted for_________________?
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A. All the above

B. Branch sewers

C. Trunk sewers

D. Main sewers

4914. In a grit chamber of a sewage treatment plant ____________________?
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A. Depth of 0.9 m to 1.20 m is kept

B. All the above

C. Flow velocity 0.15 m to 0.3 m/sec is kept

D. One minute of detention period is kept

4915. Large diameter sewers subjected to external pressure alone, are reinforced ______________________?
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A. Near the inner surface of the pipe

B. Near the outer surface of the pipe

C. Both A. and B.

D. With elliptical cage
4916. The arrangement made for passing the sewer line below an obstruction below the hydraulic gradient lines called ____________________?
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A. all of these

B. Sag pipe

C. Depressed sewer

D. Inverted syphon

4917. The small sewers are cleaned by____________________?
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A. Flushing

B. Cane rodding

C. None of these

D. Wooden pills

4918. The most efficient cross-section of sewers in a combined sewerage system is________________?
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A. Parabolic

B. Rectangular

C. Circular

D. New egged

4919. Pick up the correct statement from the following?
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A. The sewers may be carried up and down the hills and valleys

B. The water supply pipes carry pure water free from solid particles

C. The sewer pipes are generally laid along level hills

D. The water supply pipes get clogged if flow velocity is less than self cleansing velocity

4920. Oxidation process results in the formation of___________________?
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A. Carbon dioxide

B. Nitrates

C. All the above

D. Sulphates

4921. To test chemical oxygen demand (C.O.D.) of sewage, organic matter is oxidised by potassium dichromate in the presence of_______________?
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A. Sulphuric acid

B. Nitric acid

C. Hydrochloric acid

D. Citric acid

4922. Antisyphonage pipe is fitted_______________?
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A. At the beginning of sewer line

B. On manholes

C. With a W.C. trap

D. At the end of septic tanks

4923. The ratio of depths at partial flo________________?
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A. 1

B. 1

C. (1

D. (1
4924. A rain sanitary sewer is constructed to carry_________________ ?
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A. Storm sewage

B. Surface water

C. Ground water

D. Sanitary sewage
4925. In areas where rainy season is limited to a few months, the type of sewerage system recommended is__________________?
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A. Combined system

B. Separate system

C. Partially separate system

D. None of these

4926. In circular sewers if depth of flow is 0.2 times the full depth, the nominal gradient,______________?
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A. Is doubled

B. Is trebled

C. Is only provided

D. Is not enough

4927. The most efficient cross section of sewers in a separate sewerage system is__________________?
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A. Rectangular

B. New egged

C. Parabolic

D. Circular
4928. In the activated sludge process__________________?
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A. Sludge is activated by constant stirring

B. Aeration is continued till stability

C. Aeration is done with an admixture of previously aerated sludge

D. Water is removed by centrifugal action

4929. The self-cleansing velocity of water flowing through pipe lines, is___________________ ?
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A. 0.5 metre/sec

B. 1 metre/sec

C. 2 metres/sec

D. 0.25 metre/sec

4930. In normal conditions, the period for sludge digestion, is_______________?
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A. 10 days

B. 20 days

C. 60 days

D. 30 days
4931. A manhole is classified as shallow if its depth is between_________________?
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A. 0.4 to 0.5 m

B. 0.7 to 0.9 m

C. 0.9 to 1.20 m

D. 0.5 to 0.7 m

4932. In 1000 kg of sewage, the total solids approximate___________________?
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A. 5 kg to 7.5 kg

B. 0.5 to 1.0 kg

C. 1 kg to 2.0 kg

D. 7.5 kg to 10 kg

4933. In a sludge digestion tank if the moisture content of sludge V1 litres is reduced from p1 % to p2 % the volume V2 is____________________?
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A. [(100 P1)/(100 + P2)] V1

B. [(100 + P1)/(100 P2)] V1

C. [(100 P1)/(100 P2)] V1

D. [(100 + P2)/(100 P1)] V1

4934. Rate of flow of sewage is generally assumed__________________?
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A. Less than the rate of water supply

B. At 150 litres per capita

C. Equal to the rate of water supply

D. More than the rate of water supply

4935. Sewer manholes are generally provided at________________?
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A. The change of direction

B. The junctions of sewers

C. All of these

D. The change of gradient

4936. The maximum spacing of manholes specified by Indian standard in sewers upto 0.3 m diameter is____________________?
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A. 75 m

B. 30 m

C. 45 m

D. 20 m

4937. Clogging of sewers, is caused due to_______________?
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A. Low discharge

B. Greasy and oily matters

C. All the above

D. Silting

4938. The laying of sewers is done with____________________?
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A. Magnetic compass

B. Clinometer

C. Level

D. Theodolite

4939. The ratio of design discharge to the surface area of a sedimentation tank is called____________________?
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A. Overflow velocity

B. Overflow rate

C. Surface loading

D. All of these
4940. If the over land flow from the critical point to the drain is 8 km and the difference in level is 12.4 m, the inlet time is________________?
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A. 4 hours

B. 3 hours

C. 2 hours

D. 5 hours

4941. Inter-distance between ventilation columns in a sewer line is kept__________________?
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A. 50 m to 100 m

B. 100 m to 150 m

C. 25 to 50 m

D. 150 m to 300 m
4942. The normal values of over flow rates for secondary sedimentation tanks, ranges between__________________?
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A. 40,000 to 50,000 litres/sqm/day

B. 25,000 to 35,000 litres/sqm/day

C. 80,000 to 10,000 litres/sqm/day

D. 50,000 to 60,000 litres/sqm/day

4943. Bio-chemical oxygen demand (BOD) for the first 20 days in generally referred to_______________?
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A. Carbonaceous demand

B. First stage demand

C. Initial demand

D. All of these
4944. If the peak discharge of a storm water drain (S.W. Drain) is expected to exceed 150 cumecs, the free board to be provided, is_________________?
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A. 100 cm

B. 80 cm

C. 50 cm

D. 90 cm

4945. The normal value of over flow rates for plain primary sedimentation tanks, ranges between________________?
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A. 25,000 to 35,000 litres/sqm/day

B. 80,000 to 100,000 litres/sqm/day

C. 50,000 to 60,000 litres/sqm/day

D. 40,000 to 50,000 litres/sqm/day
4946. For trunk and out-fall, the type of sewers generally used, is_____________________?
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A. Horse shoe shaped

B. Circular shaped

C. Standard egg shaped

D. Parabolic shaped

4947. The standard B.O.D. of water is taken for_________________?
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A. 2 days

B. 5 days

C. 1 day

D. 3 days

4948. In a city the ratio of the drainage to sewage is 20, the percentage discharge passing through non-monsoon periods, is_____________________?
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A. 20

B. 5

C. 10

D. 15

4949. Pick up the correct statement from the following?
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A. All the above

B. Only very fresh sewage contains some dissolved oxygen

C. The solubility of oxygen in sewage is 95% that is in distilled water

D. In treated sewage, 4 ppm of D.O. is essential

4950. During purification process of sewage the gas given off, is________________?
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A. Hydrogen

B. Ammonia

C. Carbon dioxide

D. All the above