water and wastewater engineering mcq

Faculty of Degree Engineering - 083 Department of Civil Engineering - 06

Water and Wastewater Engineering MCQ 1 For a continuous flow type of sedimentation tanks

(A) Width of the tank is normally kept about 6 m

(B) Length of the tank is normally kept 4 to 5 times the width

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

(D) All the above

Ans. D

2 The asbestos cement sewers are

(A) Light in weight

(B) Not structurally strong to bear large compressive stress

(C) Susceptible to corrosion by sulphuric acid

(D) All the above

Ans. D

3 For efficient working of a sewer, it must be ensured that

(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)

Ans. C

4 Bottom openings 15 cm × 15 cm in the standing baffle wall are provided

(A) 15 cm c/c

(B) 22.5 cm c/c

(C) 30 cm c/c

(D) 50 cm c/c

Ans. B

5 For drainage pipes in buildings the test applied before putting them to use, is

(A) Water test

(B) Smoke test

(C) Straightness test

(D) All the above

Ans. B

6 The pressure exerted by

(A) The sewage when running full from inside, is called internal pressure

(B) The internal pressure if any, causes tensile stress in the pipe material

(C) Pressure sewers are designed to be safe in tension

(D) All the above

Ans. D

7 No treatment of the sewage is given if dilution factor is


(A) Less than 150

(B) Between 150 to 200

(C) Between 200 to 300

(D) More than 500

Ans. D

8 Which of the following pumps in used to pump sewage solids with liquid sewage without

clogging the pump is?

(A) Centrifugal pump

(B) Pneumatic ejector

(C) Reciprocating pump

(D) None of these

Ans. A

9 Acid regression stage of sludge digestion at a temperature 21°C extends over a period of

(A) 15 days

(B) 30 days

(C) ) 60 days

(D) 90 days

Ans. D

10 The coagulant which is generally not used for treating the sewage, is

(A) Alum

(B) Ferric chloride

(C) Ferric sulphate

(D) Chlorinated copperas

Ans. A

11 The layers of vegetable wastes and night soil alternatively piled above the ground to form a

mound, is called

(A) A heap

(B) Plateau

(C) Windrow

(D) None of these

Ans. D

12 If the flame of a miner's safety lamp in the upper layers of the sewer forms an explosive, the

sewer certainly contains

(A) Hydrogen sulphide

(B) Carbon dioxide

(C) Methane

(D) Oxygen

Ans. C

13 The gas which may cause explosion in sewers, is

(A) Carbondioxide


(B) Methane

(C) Ammonia

(D) Carbon monoxide

Ans. B

14 Pick up the incorrect statement from the following:

(A) The process of decomposing the organic matter under controlled anaerobic conditions, is

called sludge digestion

(B) Sludge digestion is carried out in sludge tank

(C) The gases produced in sludge digestion process, contain 75% carbon dioxide

(D) The gases produced in sludge digestion process, contain 75% methane

Ans. C

15 The sewer pipes

(A) Carry sewage as gravity conduits

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

(C) Should resist the wear and tear caused due to abrasion

(D) All the above

Ans. D

16 The settling velocity of the particles larger than 0.06 mm in a settling tank of depth 2.4 is 0.33 m

per sec. The detention period recommended for the tank, is

(A) 30 minutes

(B) 1 hour

(C) 1 hour and 30 minutes

(D) 2 hours

Ans. D

17 The Chezy's constant C in the formula V = C 𝑟𝑠 depends upon

(A) Size of the sewer

(B) Shape of the sewer

(C) Roughness of sewer surface

(D) All the above

Ans. D

18 To prevent settling down of sewage both at the bottom and on the sides of a large sewer,

selfcleaning velocity recommended for Indian conditions, is

(A) 0.50 m/sec

(B) 0.60 m/sec

(C) 0.70 m/sec

(D) 0.75 m/sec

Ans. D

19 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.

(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

Ans. A

20 The normal values of over flow rates for sedimentation tanks using coagulant, ranges between

(A) 25,000 to 35,000 litres/sqm/day

(B) 40,000 to 50,000 litres/sqm/day

(C) 50,000 to 60,000 litres/sqm/day

(D) 80,000 to 100,000 litres/sqm/day

Ans. C

21 The sewer that unloads the sewage at the point of treatment is called

(A) Main sewer

(B) Outfall sewer

(C) Branch sewer

(D) House sewer

Ans.

22 During preliminary treatment of a sewage

(A) Oil and grease are removed from skimming tanks

(B) Floating materials are removed by screening

(C) Girt and sand are removed by girt chambers

(D) All the above

Ans. D

23 Dry weather flow is:

(A) Average daily rate of flow

(B) Average monthly rate of flow

(C) Average annual rate of flow

(D) Water supply allowance per capita

Ans. D

24 If q is the average sewage flow from a city of population P, the maximum sewage flow

(A) Q = [(4 + 𝑝 )/(18 + 𝑝 )] q

(B) Q = [(18 +p )/(4 + 𝑝 )] q

(C) Q = [(18 + 𝑝 )/(4 + 𝑝 )] q

(D) Q = [(5 + 𝑝 )/(15 + 𝑝 )] q

Ans. D

25 If the flame of a miner's safety lamp in a manhole extinguishes within 5 minutes, the sewer

certainly contains

(A) Hydrogen sulphide


(B) Carbon dioxide

(C) Methane

(D) Oxygen

Ans. B

26 Hydraulic mean radius is

(A) Mean radius of sewer

(B) Difference in heads between two points in circular pipes

(C) Mean of radii in a pipe line of varying cross-sections

(D) Cross-sectional area/wetted perimeter

Ans. D

27 If the depth of flow in a circular sewer is 1/4th of its diameter D, the wetted perimeter is

(A) 𝝅𝑫

𝟐

(B) 𝝅𝑫

𝟒

(C) 𝝅𝑫

𝟑

(D)𝝅𝑫

Ans. C

28 At the junction of sewers

(A) Top of smaller sewer is kept lower

(B) Top of larger sewer is kept lower

(C) Tops of both the sewers are at the same level

(D) None of these

Ans. D

29 The sewage treatment units in which anaerobic decomposition of organic matter is used, are

called

(A) Imhoff tanks

(B) Trickling filters

(C) Sludge sedimentation tanks

(D) None of these

Ans. B

30 The sewer which received discharge from two or more main sewers, is known as

(A) A trunk sewer

(B) An outfall sewer

(C) A main sewer

(D) An intercepting sewer

Ans. A

31 The grit and silt of the grit chambers, may not be used for

(A) Raising low lying areas by dumping


(B) Concreting



Ans. B

32 For treating the sewage of a large city, you will recommend

(A) A sedimentation tank and an activated sludge treatment plant

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

(C) Sedimentation tanks with high rate trickling filters

(D) None of these

Ans. A

33 Imhoff cone is used to measure

(A) Total organic solids

(B) Total solids

(C) Total in organic solids

(D) Settleable solids

Ans. D

34 1000 kg of sewage contains

(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

Ans. D

35 For the COD test of sewage, organic matter is oxidised by K2 Cr2O7 in the presence of

(A) H2SO4

(B) HNO3

(C) HCl

(D) None of these

Ans. A

36 The sludge does not contain waste water from

(A) Bath rooms

(B) Wash basins

(C) Kitchen sinks

(D) Toilets

Ans. D

37 In sewers the velocity of flow should not be

(A) More than the self-cleansing velocity

(B) Less than the self-cleansing velocity

(C) Less than 10 m/sec

(D) More than 20 m/sec


Ans. B

38 In sewers the effect of scouring is more on

(A) Top side

(B) Bottom side

(C) Horizontal side

(D) All sides

Ans. B

39 The sewer which resists sulphide corrosion, is

(A) Brick sewer

(B) Cast iron sewer

(C) R.C.C. sewer

(D) Lead sewer

Ans. D

40 In a sedimentation tank (length L, width B, depth D) the settling velocity of a particle for a

discharge Q, is

(A) Q/(B × D)

(B) Q/(L × D)

(C) Q/L

(D) Q/(B × L)

Ans. D

41 The formula which accepts the value of rugosity coefficient n = 0.012 to be used in Manning's

formula, is given by

(A) Bazin

(B) Crimp and Bruges

(C) William-Hazen

(D) Kutter

Ans. B

42 The amount of oxygen consumed by the aerobic bacterias which cause the aerobic biological

decomposition of sewage, is known

(A) Bio-Chemical Oxygen Demand (B.O.D.)

(B) Dissolved Oxygen (D.O.)

(C) Chemical Oxygen Demand (C.O.D.)

(D) None of these

Ans. B

43 Water content of sewage is about

(A) 90 %

(B) 95 %

(C) 99 %

(D) 9.9 %

Ans. D


44 Skimming tanks are

(A) Used to remove the grease and oil

(B) Those from which sludge is skimmed out

(C) Tanks provided with self-cleansing screens

(D) Improved version of grit chambers

Ans. A

45 The most efficient cross-section of sewers in a combined sewerage system is

(A) ) Parabolic

(B) Circular

(C) Rectangular

(D) New egged

Ans. B

46 The detention period for plain sedimentation water tanks, is usually

(A) 4 to 8 hours

(B) 8 to 16 hours

(C) 16 to 24 hours

(D) 24 to 36 hours

Ans. A

47 The factor responsible for purification of sewage in river is

(A) Hydrology

(B) Dissolved oxygen in water

(C) Temperature

(D) All the above

Ans. D

48 Hume steel pipes are

(A) Steel pipes

(B) Steel shell coated from inside with cement mortar

(C) Steel shell coated from outside with cement mortar

(D) Both (B) and (C)

Ans. D

49 To maintain aerobic biological activity, the moisture content of the compost mass should be

about

(A) 45 %

(B) 50 %

(C) 55 %

(D) 60 %

Ans. C

50 Pick up the correct statement from the following:

(A) The larger the sewer in size, more will be

(B) The smaller the sewer in size, less will be velocity


(C) The larger the sewer in size, no deposition will take place

(D) The larger the sewer in size, deposition will take place

Ans. D

51 The pH value of sewage is determined with the help of

(A) Imhoff Cone

(B) Turbid meter

(C) Potentiometer

(D) None of these

Ans. C

52 The normal value of over flow rates for plain primary sedimentation tanks, ranges between





Ans. B

53 Which one of the following statements regarding septic tanks is wrong?

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

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

(C) The minimum width of septic level is 90 cm

(D) The depth of tank is kept equal to its width

Ans. D

54 In a trickling filter

(A) Filtration process is used

(B) Biological action is used

(C) Neither (a) nor (b)

(D) Both (a) and (b)

Ans.

55 In areas where rainy season is limited to a few months, the type of sewerage system

recommended is

(A) Combined system

(B) Partially separate system

(C) Separate system

(D) None of these

Ans. C

56 The rate of accumulation of sludge in septic tanks is recommended as

(A) 30 litres/person/year

(B) 25 litres/person/year

(C) 30 litres/person/month

(D) 25 litres/person/month

Ans. A


57 Dried sewage after treatment is used as

(A) Fertilizer

(B) Building material

(C) Chemical for lowering B.O.D.

(D) Base material for paints

Ans. A

58 For drains up to 15 cumecs, the depth “d” and “B” width are related by

(A) d = 0.2

(B) d = 0.5 B

(C) B = 0.2 d

(D) B = 0.5 d

Ans. B

59 In areas where light rains are uniformly distributed throughout the year, the type of sewerage

system to be adopted is

(A) Separate system

(B) Combined system

(C) Partially combined system

(D) None of these

Ans. B

60 Self-cleansing velocity is

(A) Velocity at dry weather flow

(B) Velocity of water at flushing

(C) Velocity at which no accumulation remains in the drains

(D) Velocity of water in a pressure filter

Ans. C

61 5 days-biochemical oxygen demand (BOD5) is taken at a temperature of

(A) 0°C

(B) 15°C

(C) 20°C

(D) 25°C

Ans. C

62 A well oxidized sewage contains nitrogen mainly as

(A) Nitrates

(B) Nitrites

(C) Free ammonia

(D) None of these

Ans. A

63 In a sludge tank, the gas mainly produced, is

(A) Oxygen


(B) Nitrogen

(C) Hydrogen

(D) Carbon dioxide

Ans. D

64 If “D” is the diameter of upper circular portion, the overall depth of New Egg shaped sewer

section, is

(A) 1.250 D

(B) 1.350 D

(C) 1.425 D

(D) 1.625 D

Ans. D

65 In normal conditions, the period for sludge digestion, is

(A) 10 days

(B) 20 days

(C) 30 days

(D) 60 days

Ans. C

66 For evaporation and measurement of settable solids, the apparatus used, is

(A) A jar

(B) A breaker

(C) A test tube

(D) An Imhoff cone

Ans. D

67 In trickling filter, B.O.D. is reduced to

(A) 30 to 40%

(B) 40 to 60%

(C) 60 to 80%

(D) 80 to 90%

Ans. C

68 For design of sewers, percentage of sewage discharge is assumed

(A) 65 to 70

(B) 70 to 75%

(C) 75 to 80%

(D) 85%

Ans. C

69 The grit chambers of sewage treatment plants, are generally cleaned after

(A) 2 days

(B) 7 days

(C) 12 days

(D) 14 days


Ans. D

70 Maximum permissible velocity 1.5 m/sec, is adopted in drains

(A) With beds of rocks and gravels

(B) Lined with stones



Ans. C

71 The average temperature of sewage in India, is

(A) 10°C (B) (C) (D)

(B) 15°C

(C) 20°C

(D) 25°C

Ans. C

72 Pick up the in-correct statement from the following:

(A) Manholes are provided in sewer pipes at suitable intervals

(B) Catch basins are generally provided in sewers for carrying drainage discharge

(C) Inlets are generally provided in all sewers

(D) None of these

Ans. C

73 A well oxidized sewage contains nitrogen mainly as

(A) Nitrates

(B) Nitrites

(C) Free ammonia

(D) None of these

Ans. A

74 The moisture content of sludge is reduced from 90% to 80% in a sludge digestion tank. The

percentage decrease in the volume of sludge, is

(A) 25 % (B) (C) (D)

(B) 50 %

(C) 10 %

(D) 5 %

Ans. B

75 In a sludge tank, the gas mainly produced, is

(A) Oxygen

(B) Nitrogen

(C) Hydrogen

(D) Carbon dioxide

Ans. D

76 If ‘D’ is the diameter of upper circular portion, the overall depth of New Egg shaped sewer

section, is


(A) 1.250 D

(B) 1.350 D

(C) 1.425 D

(D) 1.625 D

Ans. D

80 In normal conditions, the period for sludge digestion, is

(A) 10 days

(B) 20 days

(C) 30 days

(D) 60 days

Ans. C

81 For evaporation and measurement of settable solids, the apparatus used, is

(A) A jar

(B) A breaker

(C) A test tube

(D) An Imhoff cone

Ans. D

82 In trickling filter, B.O.D. is reduced to

(A) 30 to 40% (B) (C) (D)

(B) 40 to 60%

(C) 60 to 80%

(D) 80 to 90%

Ans. C

83 For design of sewers, percentage of sewage discharge is assumed

(A) 65 to 70% (B) (C) (D)

(B) 70 to 75%

(C) 75 to 80%

(D) 85%

Ans. C

84 The grit chambers of sewage treatment plants, are generally cleaned after

(A) 2 days (B) (C) (D)

(B) 7 days

(C) 12 days

(D) 14 days

Ans. D

85 In the activated sludge process

(A) Aeration is continued till stability

(B) Aeration is done with an admixture of previously aerated sludge

(C) Sludge is activated by constant stirring

(D) Water is removed by centrifugal action


Ans. B

86 For detecting the nitrates in sewage, the colour may be developed by adding

(A) Potassium permanganate (B) (C) (D)

(B) Sulphuric acid and napthamine

(C) Phenol-di-sulphuric acid and potassium hydroxide

(D) None of these

Ans. C

87 The settling velocity of a spherical particle of diameter less than 0.1 mm as per Stock's law, is

(A) Vs = 418 (Gs - Gw)d [(3T + 70)/100]

(B) Vs = 418 (Gs - Gw)d² [(3T + 70)/100]

(C) Vs = 218 (Gs - Gw)d² [(3T + 70)/100]

(D) Vs = 218 (Gs - Gw)d [(3T + 70)/100]

Ans. B

88 Inter-distance between ventilation columns in a sewer line is kept

(A) 25 to 50 m

(B) 50 m to 100 m

(C) 100 m to 150 m

(D) 150 m to 300 m

Ans. D

89 Stone ware pipes are

(A) Highly resistant to sulphide corrosion (B) (C) (D)

(B) Highly impervious

(C) Hydraulically efficient because of their smooth interior surface

(D) Especially suited to pressure pipes

Ans. D

90 The intensity of rain is expressed in

(A) cm/minute (B) (C) (D)

(B) cm/hour

(C) cm/day

(D) None of these

Ans. B

91 The ratio of the diameter of a circular section and the side of a square section hydraulically

equivalent, is

(A) 1.095

(B) 1.085

(C) 1.075

(D) 1.065

Ans. A

92 Which one of the following part of human body withstands minimum radiation?


(A) Thyroid

(B) Kidneys

(C) Eyes

(D) Ovaries/testis

Ans. D

93 Drop manholes are the manholes

(A) Without entry ladders

(B) Without manhole covers

(C) With depths more than 3.5 m

(D) Having drains at different levels

Ans. D

94 The bottom of the sewage inlet chamber of septic tanks, is provided an outward slope

(A) 1 in 5

(B) 1 in 10

(C) 1 in 15

(D) 1 in 20

Ans. B

95 Primary treatment of sewage consists of removal of

(A) Large suspended organic solids

(B) Oil and grease

(C) Sand and girt

(D) Floating materials

Ans. A

96 Cement concrete sewers are only suitable if non-scouring velocity is between

(A) ) 2.5 to 3.0 m/sec (B) (C) (D)

(B) 3.0 to 4.0 m/sec

(C) 3.5 to 4.5 m/sec

(D) 4.5 to 5.5 m/sec

Ans. A

97 The most widely used pump for lifting sewage is


(B) Reciprocating pump

(C) Pneumatic ejector

(D) Air pressure pump

Ans. A

98 Setting out the alignments of sewers may start from

(A) City

(B) Out-fall

(C) Tail end

(D) Any point


Ans. C

99 The detention time of a circular tank of diameter d and water depth H, for receiving the sewage

Q per hour, is

(A) d² (0.011d + 0.785H)/Q

(B) d (0.022d + 0.085H)/Q

(C) d (0.785d + 0.011H)/Q

(D) d (0.285d + 0.011H)/Q

Ans. A

100 Lead acetate test in sewer manhole is done to test the presence of

(A) Methane gas (B) (C) (D)

(B) Hydrogen sulphide

(C) Carbondioxide gas

(D) Diesel vapours

Ans. B

101 Anti syphonage pipe is fitted

(A) At the end of septic tanks (B) (C) (D)

(B) On manholes

(C) With a W.C. trap

(D) At the beginning of sewer line

Ans. C

102 In a grit chamber of a sewage treatment plant,

(A) Flow velocity 0.15 m to 0.3 m/sec is kept

(B) Depth of 0.9 m to 1.20 m is kept

(C) One minute of detention period is kept

(D) All the above

Ans. D

103 The ratio of maximum sewage flow to average sewage flow for mains up to 1 m in diameter, is

(A) 1.5 (B) (C) (D)

(B) 2.0

(C) 3.0

(D) 4.0

Ans. B

104 pH value of sludge during alkaline regression stage, is

(A) More than 7

(B) Less than 7

(C) Less than 6

(D) More than 6

Ans. A

105 The arrangement made for passing the sewer line below an obstruction below the hydraulic

gradient lines called


(A) Inverted syphon

(B) Depressed sewer

(C) Sag pipe

(D) all of these

Ans. D

106 Pick up the incorrect size of stone ware sewers

(A) 52.5 cm (B) (C) (D)

(B) 67.5 cm

(C) 82.5 cm

(D) None of these

Ans. D

107 Chlorination of water is done for the removal of

(A) Bacterias

(B) Suspended solids

(C) Sediments

(D) Hardness

Ans. A

108 Sludge banks are formed if sewage is disposed of in

(A) Rivers

(B) Seas

(C) Lakes

(D) None of these

Ans. B

109 The clarigesters are

(A) Circular septic tanks

(B) Rectangular septic tanks

(C) Circular Imhoff double tanks with bottom hoppers

(D) Circular Imhoff double storey tanks without bottom hoppers

Ans. D

110 The spacing of bars for perforations in coarse screens used for the treatment of sewage, is

(A) 20 mm

(B) 30 mm

(C) 40 mm

(D) 50 mm

Ans. D

111 The pH value of fresh sewage is usually

(A) Equal to 7

(B) More than 7

(C) Less than 7

(D) Equal to zero


Ans. B

112 The maximum depth of sedimentation tanks, is kept

(A) 3 m

(B) 3.5 m

(C) 4 m

(D) 4.5 m

Ans. A

113 Lead caulked joints are used for laying

(A) Stone ware pipes

(B) Earthenware pipes

(C) C.I. pipes

(D) G.I. pipes

Ans. B

114 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

(A) D' = 0.64 D

(B) D' = 0.74 D

(C) D' = 0.84 D

(D) D' = 0.94 D

Ans. C

115 The spacing of man holes along a straight portion of a sewer is 300 m, the diameter of the sewer

may be

(A) 0.9 cm

(B) 1.2 m

(C) 1.5 m

(D) > 1.5 m

Ans. D

116 The quantity of liquid waste which flows in sewers during the period of rainfall, is known

(A) Sanitary sewage

(B) Industrial waste

(C) Storm sewage

(D) None of these

Ans. C

117 Nitrogen cycle of sewage, is

(A) Liberation of ammonia-formation of nitrites-formation of nitrates-liberation of nitrogen

(B) Liberation of nitrogen-liberation of ammonia-formation of nitrites- formation of nitrates

(C) Liberation of nitrogen-formation of nitrates-formation of nitrites-liberation of ammonia

(D) Formation of nitrates-formation of nitrites-liberation of nitrates-liberation of nitrates

Ans. A

118 Depletion of ozone layer in the outer atmosphere may cause


(A) Lung cancer

(B) Skin cancer

(C) Bronchitis

(D) Heart disorder

Ans. B

119 The minimum diameter of a sewer is kept

(A) 10 cm

(B) 15 cm

(C) 20 cm

(D) 25 cm

Ans. B

120 Which one of the following gases is most significant as air pollutant?

(A) Carbondioxide (B) (C) (D)

(B) Oxygen

(C) Nitrogen

(D) Sulphur-dioxide

Ans. D

121 Hazen's formula VS = 418 (GS - Gw)d [(3T + 70)/100] is used for the settlement velocity of the

particles of diameter

(A) Less than 0.01 mm

(B) Less than 0.05 mm

(C) Less than 0.1 mm

(D) Greater than 0.1 mm

Ans. D

122 For sewers, inverted siphon is provided for

(A) One pipe

(B) Two pipes

(C) Three pipes

(D) Four pipes

Ans. C

123 For large sewers, maximum distance between manholes may be

(A) 50 m

(B) 100 m

(C) 200 m

(D) 300 m

Ans. D

124 In sewers designed with self cleansing velocity,

(A) The bottom is silted

(B) The bottom is scoured


(C) Both silting and scouring occur at the bottom

(D) Neither silting nor scouring occurs at the bottom

Ans. D

125 The value of Chezy's constant C = 157.6/(1.81 + K/ 𝒓 ) is used in

(A) Chezy's formula

(B) Bazin's formula

(C) Kutter's formula

(D) Manning's formula

Ans. B

126 Pathogens (or pathogenic bacteria’s) in water may cause

(A) Typhoid

(B) Cholera

(C) Dysentery

(D) All the above

Ans. D

127 The rate of accumulation of sludge per person per year, is

(A) 10 litres (B) (C) (D)

(B) 15 litres

(C) 20 litres

(D) 25 litres

Ans. C

128 The screens are fixed

(A) Perpendicular to the direction of flow

(B) Parallel to the direction of flow

(C) At an angle 30° to 60° to the direction of flow

(D) None of these

Ans. C

129 In circular sewers if depth of flow is 0.2 times the full depth, the nominal gradient,

(A) Is only provided

(B) Is doubled

(C) Is trebled

(D) Is not enough

Ans. B

130 In detritus tanks

(A) Flow velocity is kept 0.09 m/

(B) Detention period is kept 3 to 4 minutes

(C) Organic and inorganic materials are separated

(D) All the above

Ans. D

131 The flow velocity in detritus tanks is


(A) 0.05 m/sec

(B) 0.09 m/sec

(C) 1.25 m/sec

(D) None of these

Ans. B

132 If the side of a square sewer is 1000 mm, the diameter of a hydraulically equivalent circular

section, is

(A) 1045 mm

(B) 1065 mm

(C) 1075 mm

(D) 1095 mm

Ans. D

133 A nuisance is experienced in diluting water if dilution factor is less than

(A) 100

(B) 60

(C) 40

(D) 20

Ans. D

134 A manhole is generally provided at each

(A) Bend

(B) Junction

(C) Change of gradient

(D) All the above

Ans. D

135 The asbestos cement pipes are generally laid

(A) Horizontally

(B) Vertically

(C) At an angle of 30°

(D) At an angle of 60°

Ans. B

136 The design period in years for pumping plants, is

(A) ) 1

(B) 2 to 3

(C) 3 to 5

(D) 5 to 10

Ans. D

137 A safety lamp when inserted in the upper portion of a manhole causes flames. It indicates the

presence of

(A) Carbondioxide gas

(B) Hydrogen sulphide gas


(C) Methane gas

(D) Petrol vapours

Ans. C

138 Design period of 40 to 50 years is adopted for

(A) Branch sewers

(B) Main sewers

(C) Trunk sewers

(D) All the above

Ans. D

139 In very first stage of decomposition of the organic matter in sewage

(A) Nitrites are formed

(B) Nitrates are formed

(C) Carbondioxide is formed

(D) Ammonia is formed

Ans. D

140 In a city the ratio of the drainage to sewage is 20, the percentage discharge passing through

nonmonsoon periods, is

(A) 5

(B) 10

(C) 15

(D) 20

Ans. D

141 The self-cleansing velocity of water flowing through pipe lines, is

(A) 2 metres/sec

(B) 1 metre/sec

(C) 0.5 metre/sec

(D) 0.25 metre/sec

Ans. A

142 In case of sewer lines

(A) Water test is carried out to check water tightness of the joints

(B) Test for straightness is carried out with the help of a lamp and mirror

(C) Obstruction test is carried out with the help of smooth ball of diameter 13 mm

(D) All the above

Ans. D

143 The normal values of over flow rates for secondary sedimentation tanks, ranges between





Ans. A


144 A manhole is classified as shallow if its depth is between

(A) 0.4 to 0.5 m

(B) 0.5 to 0.7 m

(C) 0.7 to 0.9 m

(D) 0.9 to 1.20 m

Ans. C

145 The first stage of neutral process of sludge digestion, is

(A) Acid fermentation

(B) Acid regression

(C) Alkaline fermentation

(D) None of these

Ans. A

146 The formula V = (1/n) r2/3 𝒔 used for determining flow velocities in sewers is known as,

(A) Chezy's formula

(B) Bazin's formula

(C) Kutter's formula

(D) Manning's formula

Ans. D

147 In sewers the highest non-scouring velocity is achieved in

(A) Glazed bricks sewers

(B) Cast iron sewers

(C) Cement concrete sewers

(D) Stone ware sewers

Ans. A

WATER SUPPLY ENGINEERING

148 When the reduced level of the water source is higher than the reduced level of the consumer's

place, water is generally supplied

(A) By pumping system

(B) By gravitational system


(D) All the above

Ans. B

149 Surcharge storage zone of a reservoir, is

(A) Below dead storage (B) (C) (D)

(B) Between dead storage and useful storage

(C) Above useful storage

(D) Also known as valley storage

Ans. C

150 In pressure supply mains, water hammer pressure is reduced by providing


(A) Sluice valves

(B) Air valves

(C) Pressure relief valves

(D) None of these

Ans. C

151 Specific capacity or yield of wells, is generally expressed, as

(A) m 3 per sec

(B) m 3 /hour

(C) m 3 /hour/m2

(D) m 3 /hour/m2 /m

Ans. D

152 Turbidity of raw water is a measure of

(A) Suspended solids

(B) Acidity of water

(C) B.O.D.

(D) None of these

Ans. A

153 If the chosen diameter of a pipe, is less than the economical diameter

(A) Cost of pipe will be less

(B) Head loss will be high

(C) Cost of pumping will be more than saving

(D) All the above

Ans. D

154 While determining the yield of open wells by the pumping test

(A) Velocity of recharging water, increases with depression head

(B) Depression head resulting at critical velocity, is called critical depression head

(C) Working head is generally limited to 1/3 rd of the critical depression head

(D) Maximum safe yield of an open well, is expected at critical depression head

Ans. D

155 The process of passing water through beds of granular materials, is called

(A) Screening

(B) Sedimentation

(C) Filtration

(D) None of these

Ans. C

156 For the prediction of future population of a city, the factor to be considered, is

(A) Births

(B) Deaths

(C) Migrants

(D) All the above


Ans. D

157 Mathamoglobinemia or blue baby disease is caused due to

(A) Chlorides

(B) Nitrites

(C) Nitrates

(D) Sulphides

Ans. C

158 To control the growth of algae in reservoirs, the compound which is used, is

(A) Bleaching powder

(B) Copper sulphate

(C) Lime solution

(D) Alum solution

Ans. B

159 A pressure conduit laid underground, may not be subjected to

(A) Internal pressure of water

(B) Pressure due to external load

(C) Longitudinal temperature stress

(D) Longitudinal stresses due to unbalanced pressure to bends

Ans. C

160 The bacterias which require free oxygen for their survival, are called

(A) Aerobic bacterias

(B) Anaerobic bacterias

(C) Facultative bacteria

(D) None of these

Ans. A

161 Gravity conduits are generally in the form of

(A) Canals

(B) Flumes

(C) Aqueduct

(D) All the above

Ans. D

162 The bed slope in slow sand filters, is generally kept

(A) 1 in 50

(B) 1 in 75

(C) 1 in 100

(D) 1 : 200

Ans. C

163 Perched aquifers are generally found

(A) On the surface of the ground

(B) Below the surface of the ground but above water table


(C) Below the water table

(D) All the above

Ans. B


(A) The pH value of water indicates the logarithm of reciprocal of hydrogen ion concentration in

water

(B) Higher value of pH means lower hydrogen ion concentration

(C) Lower value of pH means higher hydrogen ion contraction

(D) Lower value of pH gives alkaline solution

Ans. D

165 Mostly used coagulant, is

(A) Chlorine

(B) Alum

(C) Lime

(D) Bleaching powder

Ans. B

166 A centrifugal pump is required to be primed before starting if it is located

(A) At higher level than water level of reservoir

(B) At lower level than water level of reservoir



Ans. A

167 Normal values of overflow rate for plain sedimentation tank, is

(A) 250 to 500 litres/hr/m2

(B) 500 to 750 litres/hr/m2

(C) 750 to 1000 litres/hr/m2

(D) 1000 to 1250 litres/hr/m2

Ans. B

168 'Shrouding' is essentially provided in

(A) Strainer type wells

(B) Cavity type wells

(C) Slotted type well

(D) All the above

Ans. C

169 The maximum permissible hardness for public supplies is

(A) 95 mg/litre

(B) 105 mg/litre

(C) 115 mg/litre

(D) 125 mg/litre

Ans. C


170 The chlorine supply cylinders are generally kept at 38°C to 40°C to prevent

(A) Conversion into crystals

(B) It from burning

(C) It from explosion

(D) None of these

Ans. A

171 For calculation of economical diameter D of a pipe in metres for a discharge Q to be pumped in

cumecs, Lea suggested the empirical formula

(A) D = 0.22 𝑄

(B) D = 1.22 𝑄

(C) D = 2.22 𝑄

(D) D = 3.22 𝑄

Ans. B

172 An earth formation which, although porous and capable of absorbing water does not provide an

appreciable supply to wells, is known as

(A) Aquifer

(B) Aquiclude

(C) Aquifuge

(D) None of these

Ans. B

173 Property of earth to allow water to pass through it, is known as

(A) Perviousness

(B) Porosity

(C) Permeability

(D) Transmissibility

Ans. A

174 If G is the specific gravity of particles of diameter d, the velocity of settlement V in still water at

T°C, according to Stoke's law, is

(A) V = 418 (G - 1) d² [(3T + 70)/100]

(B) V = 418 (G - 1) d [(3T - 70)/100]

(C) V = 418 (G - 1) d² [(2T + 70)/100]

(D) V = 418 (G - 1) d 4 [(3T + 70)/100]

Ans. A

175 Distribution mains of any water supply, is normally designed for its average daily requirement

(A) 100 %

(B) 150 %

(C) 200 %

(D) 225 %

Ans. D


176 Maximum threshold number permitted for indicating the odour of public water supplies, is

(A) 1

(B) 2

(C) 3

(D) 4

Ans. C

177 The rate of silting in a reservoir

(A) Is less in the beginning

(B) Remains constant throughout

(C) Is more in the beginning

(D) is more in the beginning and reduces in the end

Ans. D

178 Corrosion of well pipes may not be reduced by

(A) Reducing the draw down and the pumping rate

(B) Reducing the flow velocity

(C) Using thicker pipes

(D) Using screens having larger area of openings

Ans. D

179 Recuperation test is carried out to determine

(A) Turbidity of water

(B) pH value of water

(C) Yield of well

(D) Discharge from a well

Ans. A

180 Pick up the incorrect statement from the following. The underground sources of water, is from

(A) Wells

(B) Springs

(C) Infiltration wells

(D) Storage reservoirs

Ans. D

181 Most important method for calculating discharge for planning a water supply project, is

(A) Velocity area method

(B) Weir or spillway method

(C) Use of venturi-meter

(D) Using power plant consumption

Ans. A

182 In a rapid sand filter, air binding is caused due to excessive

(A) Negative pressure

(B) Pressure

(C) Turbidity


(D) Water pressure

Ans. A

183 One degree of hardness of water means a content of salts of

(A) 10.25 mg/litre

(B) 12.25 mg/litre

(C) 14.25 mg/litre

(D) 16.25 mg/litre

Ans. C

184 The U.C. (uniformity coefficient) D60/D10 for the best filter media sand should be

(A) 2

(B) 3

(C) 4

(D) 5

Ans. A

185 Manholes are less common in

(A) Cast iron pipes

(B) Steel pipes

(C) Hume steel pipes

(D) R.C.C. pipes

Ans. A

186 For determining the velocity of flow of underground water, the most commonly used

nonempirical formula is

(A) Darcy's formula

(B) Slichter's formula

(C) Hazen's formula

(D) Lacy's formula

Ans. A

187 The most commonly used chemical for de-chlorination of water, is

(A) Sodium thiosulphate

(B) Sodium bisulphate

(C) Sodium sulphite

(D) Sulphur-dioxide

Ans. C

188 To remove very fine suspended particles from water, the method adopted is

(A) Screening

(B) Sedimentation

(C) Boiling

(D) Filtration

Ans. D


189 Sunlight

(A) Helps growth of bacterias

(B) Impedes growth of algae

(C) Increases dissolved oxygen content

(D) Reduces turbidity

Ans. B

190 The detention period for plain sedimentation water tanks, is usually

(A) 4 to 8 hours

(B) 8 to 16 hours

(C) 16 to 24 hours

(D) 24 to 36 hours

Ans. D

191 Air valves are generally provided in pressure pipes of water supply

(A) At pipe junctions (B) (C) (D)

(B) At summits

(C) At low points

(D) Near service pipes

Ans. B

192 The gaseous form of chlorine gets converted into liquid form when subjected to a pressure of

(A) 5 kg/cm2

(B) 6 kg/cm2

(C) 7 kg/cm2

(D) 10 kg/cm2

Ans. C

193 Flow through period, in sedimentation tanks, is

(A) Equal to detention period

(B) More than detention period

(C) Less than detention period

(D) Detention period divided by displacement efficiency

Ans. C

194 The maximum hourly consumption, is generally taken as

(A) 110 %

(B) 120 %

(C) 140 %

(D) 150 %

Ans. D

195 Hardness of water can be removed by boiling if it is due to

(A) Calcium bicarbonates

(B) Calcium sulphates

(C) Calcium chloride


(D) Calcium nitrates

Ans. A

196 Hardness of water is caused by

(A) Presence of soap lather

(B) Presence of chlorides and sulphates of sodium and potassium

(C) Presence of bicarbonates, sulphates or chlorides of calcium and magnesium

(D) Turbidity

Ans. C

197 The average domestic consumption under normal conditions in an Indian city per day per

person, is

(A) 105 litres

(B) 115 litres

(C) 125 litres

(D) 135 litres

Ans. D

198 If d is the diameter of the pipe, p is the total internal pressure, f is the permissible tensile stress

and n is the effective of the joint, the thickness t of metal pipe, is

(A) n (pd/2f)

(B) (1/n) (pd/2f)

(C) (1/n) (pd/3f)

(D) (1/n) (pf/d)

Ans. B

199 Generally, first portion of a logistic curve for the population growth of a developing city,

represents the growth of

(A) Increasing

(B) Decreasing

(C) Constant

(D) All the above

Ans. A

200 A pressure conduit carrying water beneath a stream or a canal, is known as

(A) Sag (B) (C) (D)

(B) Depressed pipe

(C) Inverted syphon

(D) All the above

Ans. D

201 Most satisfactory formula for an estimate of fire demand Q for a city of population P in

thousands for Indian conditions, is

(A) Q = 1115 (p/5 + 20)

(B) Q = 1640 𝑃 (1 - 0.01 𝑃)


(C) Q = 3180 𝑃

(D) None of these

Ans. C

202 Permanent hardness of water can be removed by

(A) Adding alum

(B) Adding lime

(C) Adding chlorine

(D) Zeolite process

Ans. D

203 The maximum depth of sedimentation tanks is limited to

(A) 2 m (B) (C) (D)

(B) 3 m

(C) 5 m

(D) 6 m

Ans. D

204 Pick up the incorrect statement from the following. Intake of water supply should

(A) Be nearer to the treatment plant

(B) Receive water from purer zone of the source

(C) Be located downstream of waste water disposal point

(D) Remain easily accessible during floods

Ans. C

205 The fire demand of a city may be worked out by

(A) Kuichling's formula

(B) Freeman formula

(C) Under Writers formula

(D) All the above

Ans. D

206 The formula HL = n²V²L/R4/3 for the head loss in conduits is generally known as

(A) Hazen-William's formula

(B) Manning's formula

(C) Darcy-Weisbach formula

(D) Nikuradse formula

Ans. B

207 The joint used for joining the plain ends of cast iron pipes, is

(A) Flanged joint

(B) Socket and spigot joint

(C) Dresser coupling joint

(D) Flexible joint

Ans. C


208 Disinfection of water with ozone is not good because

(A) It vanishes before water reaches the consumers

(B) It removes the colour, taste and odour from water as bacterias

(C) It adds taste to the water

(D) It is more efficient than chlorine in killing bacterias

Ans. D

209 The prescribed hardness limit of potable water ranges between

(A) 50 to 75 P.P.M.

(B) 75 to 115 P.P.M.

(C) 100 to 150 P.P.M.

(D) 150 to 200 P.P.M.

Ans. B

210 While designing a water supply of an industrial township, industrial and commercial water

demand of total supply, is assumed

(A) 10 % (B) (C) (D)

(B) 10 to 15 %

(C) 15 to 20 %

(D) 20 to 25 %

Ans. D

211 After cleaning a slow sand filter, the filtered water is not used for

(A) 6 hours to 12 hours

(B) 12 hours to 18 hours

(C) 18 hours to 24 hours

(D) 24 hours to 36 hours

Ans. D

212 The efficiency of sedimentation tank does not depend upon

(A) Depth of tank

(B) Length of tank

(C) Detention period

(D) Velocity of water

Ans. D

213 Velocity of flow of water in plain sedimentation water tank, is normally kept

(A) 3 cm/minute

(B) 10 cm/minute

(C) 20 cm/minute

(D) 30 cm/minute

Ans. D

214 The depth of the water table at a place is 45 m below the general ground level. To lift water

from a deep tube well in such a locality, the type of pump to be installed is




(C) Deep well turbine pump

(D) None of these

Ans. C

215 In a well planned city, the layout of distribution pipes generally adopted, is

(A) Grid-iron system

(B) Interlaced system

(C) Reticulation system

(D) All the above

Ans. D


(A) Free surface ground water is subjected to atmospheric pressure

(B) Water table surface rises and falls with seasons

(C) Depth of water table is directly proportional to the rate of drawl of water

(D) Level of water table remains stationary

Ans. D


(A) The flow in strainer type wells is radial (B) (C) (D)

(B) The flow in cavity type wells in spherical

(C) In strainer type wells, area of flow depends upon the length of the strainer pipe

(D) In cavity type wells, area of flow depends upon the size of the cavity

Ans. C

218 As per IS : 1172-1963, water required per head per day for average domestic purposes, is

(A) 50 litres

(B) 65 litres

(C) 85 litres

(D) 135 litres

Ans. D

219 The duration of contact of chlorine with water before it is served to the first consumer, should

be at least

(A) 10 to 15 minutes

(B) 15 to 20 minutes

(C) 20 to 30 minutes

(D) 30 to 40 minutes

Ans. C

220 Water supply system includes

(A) Digging a well for water

(B) Construction of dams

(C) Construction of canals

(D) Entire arrangement from source to distribution


Ans. D

221 The maximum pressure to which a pipe is subjected to during its operation, is known

(A) Working pressure

(B) Design pressure

(C) Test pressure

(D) Pipe pressure

Ans. A

222 For the same draw down in two observations wells at distances r1 and r2, the times after start

of pumping are t1 and t2 hours respectively. The relation which holds good is

(A) t2 = r2/r1 × t1

(B) t2 = (r2/r1)² × t1

(C) t2 = (r2/r1)3 × t1

(D) t2 = (r2/r1) × t12

Ans. B

223 A slow sand filter is cleaned if its filter head is higher than

(A) 10 cm to 20 cm

(B) 20 cm to 40 cm

(C) 40 cm to 70 cm

(D) 70 cm to 120 cm

Ans. D

224 The intake opening is generally covered by a screen to prevent entry of debris etc. and its level

is kept

(A) At the level of water of the source

(B) At the bottom of water of the source

(C) At about 2.5 m above the bottom

(D) None of these

Ans. C

225 If four fires break out in a city of population 40 lakhs and if each hydrant has three streams and

duration of each fire is four hours, the total quantity of water required, is

(A) 1880 kilo litres

(B) 2880 kilo litres

(C) 3880 kilo litres

(D) 4880 kilo litres

Ans. B

226 Steel pipe are

(A) Suitable for withstanding high internal pressure

(B) Connected by riveted or welded joints

(C) Generally laid underground and no expansion joint is required


(D) Likely to last 100 years under ordinary conditions

Ans. D

227 When gravity and pumping systems of water distribution are adopted, the type of distribution

reservoir, is

(A) Elevated tank

(B) Ground source reservoir

(C) Intz tank

(D) Stand pipe

Ans. A

228 The force which develops in a pressure conduit supported on trestles, is

(A) Tension

(B) Compression

(C) Temperature stress

(D) Flexural stress

Ans. D

229 Standard unit of turbidity of water is in one litre of distilled water, one milligram of finely

divided

(A) Silica

(B) Mud

(C) Clay

(D) Organic matter

Ans. A

230 For complete stabilisation of organic matter in polluted water, it takes

(A) 5 days

(B) 10 days

(C) 20 days

(D) 30 days

Ans. D

231 If intensity of rainfall in cm per hour is I, percentage coefficient of run-off is P, area of catchment

in square kilometres is A, the total run-off Q, is given by

(A) Q = 1.758 × 102 × API (B) (C) (D)

(B) Q = 2.758 × 102 × API

(C) Q = 2.758 × 103 × API

(D) Q = 2.758 × 103 × A/PI

Ans. C

232 Shales are

(A) Porous

(B) Permeable


(C) Porous and permeable

(D) Porous but not permeable

Ans. D

233 The best process of disinfection of public water supply, is by

(A) Boiling

(B) Chlorination

(C) Adding lime

(D) Adding ozone

Ans. B

234 The dilution ratio at which the odour is hardly detectable is generally called threshold odour

number and for public supplies it should not exceed

(A) 3

(B) 5

(C) 7

(D) 9

Ans. A

235 Surge tanks are used

(A) For storage water

(B) To increase the velocity in a pipeline

(C) As overflow valves

(D) To guard against water hammer

Ans. D

236 Normal values of overflow rate for plain sedimentation tanks in litres/hr/m2 , generally range

between

(A) 100 to 250

(B) 250 to 500

(C) 500 to 750

(D) 750 to 1000

Ans. C

237 P.V.C. pipes can withstand pressure bead of water upto

(A) 25 m

(B) 50 m

(C) 75 m

(D) 100 m

Ans. D

238 Most commonly used pump for lifting water in water supply mains, is

(A) Axial flow pump


(C) Rotary type pump


(D) Centrifugal pumps

Ans. A

239 The fire demand for a city of 50,000 populations, according to Godrich formula, is

(A) 40 mld

(B) 42 mld

(C) 44 mld

(D) 48 mld

Ans. C

240 If V is total consumption of water in litres for a population of N individuals, per capita

consumption or water allowance for the water supply Q, is given by

(A) Q = V/12N

(B) Q = V/24N

(C) Q = V/265N

(D) None of these

Ans. C

241 For controlling algae, the most commonly used chemical, is

(A) Copper sulphate

(B) Alum

(C) Lime

(D) Bleaching powder

Ans. A

242 The storage capacity of a reservoir may be divided into three zones. The lowest zone is

(A) Dead storage

(B) Useful storage

(C) Surcharge storage

(D) None of these

Ans. A

243 Economic height of a dam is the height corresponding to which

(A) Cost of the dam per unit of storage is minimum

(B) Amount of silting is less

(C) Cost of dam per unit storage is maximum

(D) Free board provided is least

Ans. A

244 For maximum alkalinity of water, pH value should be

(A) Zero

(B) Less than 7

(C) More than 7

(D) 14

Ans. D

245 The efficiency of a pumping set, is generally assumed


(A) 50 %

(B) 55 %

(C) 60 %

(D) 65 %

Ans. D

246 The population growth curve is

(A) S-shaped curve

(B) Parabolic curve

(C) Circular curve

(D) Straight line

Ans. A

247 The fire demand for ascertaining the empirical formula 1136.5 [(P/10) + 10] known as

(A) Kuichling's formula

(B) Buston's formula

(C) Freeman formula

(D) Under Writers formula

Ans. C

248 The bacterias which may survive with or without free oxygen, are called



(C) Facultative bacteria's

(D) None of these

Ans. C

249 Aeration of water is done to remove

(A) Odour

(B) Colour

(C) Bacterias

(D) Turbidity

Ans. A

250 The maximum pressure to which cast iron pipes may be subjected to, is

(A) 3 kg/cm2

(B) 5 kg/cm2

(C) 7 kg/cm2

(D) 10 kg/cm2

Ans. C

251 Water may not contain much impurity if its source is

(A) Reservoirs

(B) Stream flowing in plains


(C) Lakes in lower regions

(D) Spring along hill slopes

Ans. D

252 If p is total internal pressure, d is diameter of pressure conduit and t is thickness of conduit, the

Hoop's stress is

(A) 𝜋𝑑𝑝/𝑡

(B) 𝜋𝑑𝑝/2𝑡

(C) dp/2t

(D) dt/2p

Ans. C

253 Turbidity of water is expressed

(A) In ppm

(B) In numbers in an arbitrary scale

(C) By pH value

(D) By colour code

Ans. A

254 In plain sedimentation tanks under normal conditions, impurities are removed upto

(A) 60 %

(B) 70 %

(C) 80 %

(D) 90 %

Ans. B

255 In slow sand filters, the turbidity of raw water can be removed only up to

(A) 60 mg/litre

(B) 75 mg/litre

(C) 100 gm/litre

(D) 150 mg/litre

Ans. A

256 Pressure relief valves are provided in water mains

(A) To reduce the pressure

(B) At low points

(C) Upstream of sluice

(D) All the above

Ans. D

257 Biochemical Oxygen Demand (B.O.D.) of safe drinking water must be

(A) Nil

(B) 5

(C) 10

(D) 15

Ans. A


258 At break point of chlorination,

(A) Chlorine is used to oxidise

(B) Residual chloride is zero

(C) Residual chloride is maximum

(D) Residual chlorine reappears

Ans. D

259 The capability of a soil mass of full width and depth to transmit water, is known

(A) Porosity

(B) Permeability

(C) Transmissibility

(D) None of these

Ans. B

260 By boiling water, hardness can be removed if it is due to

(A) Calcium sulphate

(B) Magnesium sulphate

(C) Calcium nitrate

(D) Calcium bicarbonate

Ans. D

261 Percussion drilling is unsuitable in

(A) Unconsolidated sand

(B) Unconsolidated gravel

(C) Quick sand

(D) Consolidated rocks

Ans. D

262 Rapid gravity filters can remove bacterial impurities up to a maximum of

(A) 50 %

(B) 60 %

(C) 70 %

(D) 80 %

Ans. D

263 Continuous flow of water can be expected from

(A) Gravity springs

(B) Surface springs

(C) Artesian springs

(D) None of these

Ans. C

264 Reciprocating pumps

(A) Are not suitable for variable heads

(B) Are four times costlier than centrifugal pumps

(C) Are not suitable for pumping water containing sediments


(D) Single stroke produce pulsating flow

Ans. A

265 Low turbidity of water is detected by

(A) Turbidity tube

(B) Jackson turbidity meter

(C) Baylis turbidimeter

(D) Hellige turbidimeter

Ans. C

266 Silt storage is the same as

(A) Dead storage

(B) Live storage

(C) Effective storage

(D) None of these

Ans. A

267 The type of pipe commonly used in water supply distribution schemes, is

(A) R.C.C. pipes

(B) Hume pipes

(C) Cast iron pipes

(D) G.I. pipes

Ans. C

268 Pick up the incorrect statement from the following. The source of surface water is from

(A) Streams and rivers

(B) Storage reservoirs

(C) Springs

(D) Ponds and lakes

Ans. C

269 The discharge Q = 2𝜋𝐾𝐻𝑆/2.3 log10 (R/rw) for the confined tube well is obtained from

(A) Thiem's formula

(B) Darcy's formula

(C) Tolman's formula

(D) Dupuits formula

Ans. D

270 m and n are monsoon duration factor and catchment factor respectively. If P is yearly rainfall in

cm, runoff can be calculated by

(A) Velocity area method

(B) Weir or spillway method

(C) Use of venturi-meter

(D) Using power plant consumption

Ans. A

271 In a rapid gravity filter


(A) Raw water from the source is supplied

(B) Disinfected raw water is supplied

(C) Raw water passed through coagulation tank is supplied

(D) None of these

Ans. C

272 The maximum permissible nitrites in public water supplies, is

(A) Nil

(B) 0.5 P.P.M.

(C) 1.0. P.P.M.

(D) 1.5 P.P.M.

Ans. A

273 Most commonly used section in grade aqueducts, is

(A) Circular

(B) Rectangular

(C) Parabolic

(D) Horse shoe section

Ans. B

274 The most important and widely used tube well in India, is

(A) Strainer well

(B) Cavity well

(C) Slotted well

(D) Perforated pipe well

Ans. A

275 Critical time for developing a water hammer, is the time required for

(A) Closing the valve

(B) The wave to travel from valve to the reservoir

(C) The wave to travel from the valve to the reservoir and back

(D) None of these

Ans. C

276 Bacterias which can survive with or without free oxygen, are known



(C) Facultative bacterias

(D) None of these

Ans. C

277 The standard B.O.D. at 20°C, is taken for the consumption in

(A) 2 days

(B) 3 days

(C) 4 days

(D) 5 days


Ans. D

278 Distribution of wash water is provided in

(A) Sedimentation tank

(B) Slow sand filter

(C) Rapid gravity filter

(D) All the above

Ans. C

279 If P is population of a city in thousands and Q is fire demand in litres per minute, for proper

estimate of water, the Empirical formula Q = 1135 [(P/5) + 10] is suggested by

(A) National Board of fire under-writers

(B) Freeman

(C) Kuichling

(D) None of these

Ans. B

280 During treatment of water, sedimentation is done

(A) Before filtration

(B) After filtration

(C) Simultaneously with filtration

(D) Along with chlorination

Ans. A

281 The ratio of the maximum daily consumption to the average daily demand, is

(A) 1.0

(B) 1.2

(C) 1.4

(D) 1.8

Ans. D

282 From the surface of reservoir, evaporation may be minimized by sprinkling

(A) Spirit

(B) Hydrochloric acid

(C) Acetyl alcohol

(D) Methane

Ans. C

283 The transitional middle portion of a logistic curve follows

(A) A geometric growth

(B) A logarithmic growth

(C) A first over curve

(D) A constant rate

Ans. D

284 For plain chlorination of water, the quantity of chlorine used, is

(A) 0.1 mg/litre


(B) 0.2 mg/litre

(C) 0.3 mg/litre

(D) 0.5 mg/litre

Ans. D

285 In distribution pipes, air valves are provided at

(A) Lower points

(B) Junction points

(C) Higher points

(D) Anywhere

Ans. C

286 Manholes along the mains from the source to a city are provided at 500 m intervals in

(A) Steel pipes

(B) R.C.C. pipes

(C) Hume steel pipes

(D) All the above

Ans. D

287 The maximum permissible colour for domestic supplies based on cobalt scale, is

(A) 5 ppm

(B) 10 ppm

(C) 15 ppm

(D) 20 ppm

Ans. D

288 Increase in population of a rapidly growing city, may be estimated by

(A) Arithmetical mean method

(B) Geometrical method

(C) Incremental increase method

(D) Graphical comparison method

Ans. B

289 Per capita demand of water is calculated in litres

(A) Per person per day

(B) Per person per month

(C) Per person per year

(D) None of these

Ans. A

290 Hard water for public water supply is discarded because

(A) ) It consumes more soap

(B) It contains lot of turbidity

(C) It contains pathogenic bacterias

(D) It possesses bad taste and odour

Ans. A



(A) Iron salts produce heavy flocks and hence remove more suspended matter

(B) Iron salts remove hydrogen sulphides

(C) Iron salts can be used over a limited range of pH values

(D) Iron salts impart corrosiveness to water

Ans. C

292 Asbestos pipes are

(A) Light in weight and easy to transport

(B) Highly resistant to corrosion

(C) High flexible to accommodate deflection upto 12°

(D) All the above

Ans. D

293 A strainer type well sunk through three previous layers intervened by three impervious

aquicludes, draws water from

(A) Top most pervious layer

(B) Central pervious layer

(C) Lowest pervious layer

(D) All the pervious layers

Ans. D

294 Runoff is the quantity of water which flows

(A) In sewer pipes

(B) Due to leakage in pipes

(C) In rivers

(D) None of these

Ans. C

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water and wastewater engineering mcq

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