500+ Solved MCQ’s on Waste Water Engineering For 2023

1. Water contains

A. one hydrogen atom and one oxygen atom
B. two hydrogen atoms and one oxygen atom
C. one hydrogen atom and two oxygen atoms
D. three hydrogen atoms and two oxygen atoms
E. two hydrogen atoms and three oxygen atoms.
Answer: B

2.  Unit Hydrograph theory was enunciated by

A. Merril Bernard
B. W.W. Horner
C. Le-Roy K. Shermen
D. Robert E. Horten.
Answer: C

3. The theory of infiltration capacity was given by

A. Merrill Bernard
B. W.W. Horner
C. Le-Roy K. Shermen
D. Robert E. Horten.
Answer: D

4. Hydrology helps in

A. predicting maximum flows
B. deciding the minimum reservoir capacity
C. forecasting the availability of quantity of water at reservoir site
D. predicting the effects on the river water level on completion of dams
E. all the above.
Answer: E

5. Pick up the correct statement from the following :

A. Rivers, lakes, oceans and springs get water from the rains
B. Rain water is obtained by evaporation from rivers, lakes and oceans
C. Water remains in atmosphere as vapours
D. Hydrologic cycle is a continuous process of evaporation and precipitation of water in atmosphere
E. all the above.
Answer: E

6. Pick up the correct statement from the following :

A. Rain which is intercepted by buildings, vegetations and other objects, is generally known as rainfall interception
B. The difference between the total rainfall and intercepted rainfall, is generally called ground rainfall
C. When rainfall exceeds the interception rainfall, water reaches the ground and infiltration starts
D. The maximum rate of absorbing water by the soil in any given condition, is known as infiltration capacity
E. All the above.
Answer: E

7. The surface Run-off is the quantity of water

A. absorbed by soil
B. intercepted by buildings and vegetative cover
C. required to fill surface depressions
D. that reaches the stream channels
E. that gets evaporated.
Answer: D

8. Pick up the correct equation from the following :

A. Run off = Surface run off + Ground water flow
B. Run off = Surface run off – Ground water flow
C. Run off = Surface run off / Ground water flow
D. Run off = Surface run off x Ground water flow.
Answer: A

9. Infiltration capacity of soil depends upon

A. number of voids present in the soil
B. shape and size of soil particles
C. arrangement of soil particles
D. compaction of the soil particles
E. all the above.
Answer: E

10. Pick up the correct statement from the following :

A. When rainfall rate exceeds the infiltration capacity, the water enters the soil at full capacity rate
B. When rainfall rate is less than the infiltration capacity, the infiltration rate is approximately equal to the rainfall rate
C. The actual infiltration rate at any time may be equal to or less than the infiltration capacity
D. The actual prevailing rate of infiltration of water in the soil at any time, is known as infiltration rate
E. All the above.
Answer: E

11. Pick up the correct statement from the following :

A. The portion of pellicular water which remains unutilised, is called hygroscopic water
B. The moisture content at which permanent wilting of plants takes place, is called the wilting point
C. The path of the water required to bring the soil moisture content of a soil up to its field capacity is called soil moisture deficiency
D. The moisture deficiency will be different at different points
E. All the above.
Answer: E

12. The main factor which affects the infiltration capacity, is

A. thickness of saturated layer
B. depth of surface detention
C. soil moisture
D. all the above.
Answer: D

13. Pick up the correct statement from the following :

A. Absolute humidity at a given temperature is equal to weight of moisture present in a unit volume
B. Relative humidity is the ratio of actual vapour pressure and saturation vapour pressure at the same temperature
C. Relative humidity is the ratio of the weight of the vapours present per unit volume to the weight of vapours which could be contained at the same temperature when fully saturated
D. Humidity can be measured by psychrometer
E. All the above.
Answer: E

14. Absolute humidity in air

A. decreases at higher altitudes
B. increases at higher altitudes
C. remains constant at all altitudes
D. none of these.
Answer: A

15. Precipitation caused by lifting of an air mass due to the pressure difference, is called

A. cyclonic precipitation
B. convective precipitation
C. orographic precipitation
D. none of these.
Answer: A

16. The standard height of a standard rain gauge, is

A. 10 cm
B. 20 cm
C. 30 cm
D. 50 cm.
Answer: C

17. In India, rain fall is generally recorded at

A. 8 A.M.
B. 12 Noon
C. 4 P.M.
D. 8 P.M.
Answer: A

18. A recording type rain gauge

A. produces a mass curve of rain fall
B. records the cumulative rain
C. is sometimes called integrating rain gauge or continuous rain gauge
D. all the above.
Answer: D

19. In India the recording type rain gauge generally used, is

A. weighing type
B. tipping type
C. float recording type
D. none of these.
Answer: C

20. The deficiency in rain catch due to vertical acceleration of air forced upward over the gauge, is

A. greater for heavy rain
B. greater for lighter rain
C. greater for large drops
D. lesser for small rain drops.
Answer: B

21. If a gauge is installed perpendicular to the slope, its measurement is reduced by multiplying

A. sine of the angle of inclination with vertical
B. cosine of the angle of inclination with vertical
C. tangent of the angle of inclination with vertical
D. calibration coefficient of the gauge.
Answer: B

22. For determination of average annual precipitation in a catchment basin, the best method is

A. Arithmetical method
B. Thiessen’s mean method
C. Isohyetal method
D. None of these.
Answer: C

23. While calculating the average depth of annual precipitation in a catchment basin, importance to individual raingauge station is given in

A. Arithmetical method
B. Thiessen’s mean method
C. Isohyetal method
D. both (a) and (b)
E. both (b) and (c).
Answer: E

24. The critical depth in a channel can be produced

A. by raising the bottom of the channel
B. by lowering the bottom of the channel
C. by decreasing the width of the channel
D. by increasing the width of the channel
E. both (a) and (c) of above.
Answer: E

25. If y is the depth of water at any section, then the mean velocity is

A. 0.1 y
B. 0.2 y
C. 0.3 y
D. 0.5 y
E. 0.6 y.
Answer: E

26. The run off is affected by

A. type of precipitation
B. rain intensity and duration of rainfall
C. rain distribution and soil moisture deficiency
D. direction of prevailing storm
E. all the above.
Answer: E

27. The initial basin recharge is equal to

A. interception
B. depression storage
C. rain absorbed by the moisture deficiency
D. all the above.
Answer: D

28. A hydraulic jump in a control meter will be formed above the control, if its original

A. depth is more than critical depth
B. depth is less than the critical depth
C. depth is equal to critical depth
D. none of these.
Answer: B

29. The run off a drainage basin is

A. Initial recharge + ground water accretion + precipitation
B. Precipitation + ground water accretion + initial recharge
C. Precipitation – ground water accretion + initial recharge
D. Precipitation – ground water accretion – initial recharge.
Answer: D

30. For computing the run off volumes of large areas, number of infiltrations used are

A. 2
B. 3
C. 4
D. 5
Answer: A

31. From the Survey of India map, the distance of the critical point is 20 km and difference in elevation is 193 m. The over land flow time, is

A. 2 hours
B. 3 hours
C. 2 hours and 30 minutes
D. 3 hours and 30 minutes
E. 4 hours.
Answer: E

32. If the area of storm hydrograph is equal to 102 cm, the ordinates of a unit hydrograph may be obtained by dividing the ordinates of the storm hydrograph by

A. 0.5
B. 1
C. 2
D. 3
E. 4
Answer: E

33. If the potential infiltration of a water shed having a soil with fair pasture cover, is 10 cm and rainfall is 12 cm, the direct run off is :

A. 2 cm
B. 3 cm
C. 5 cm
D. 8 cm.
Answer: C

34. The quantity of water retained by the sub-soil against gravity, is known

A. yield
B. porosity
C. specific yield
D. specific retention
E. none of these.
Answer: D

35. Pick up the incorrect statement from the following :

A. The rate of flow of water through a unit cross-sectional area under a unit hydraulic gradient, is called coefficient of permeability
B. The rate of flow of water through a vertical strip of the acquifer of unit width and full depth under a unit hydraulic gradient, is called coefficient of transmissibility
C. The flow of water through acquifers, is governed by the Darcy’s law
D. The term ‘transmissibility’ was introduced by Meinzer
E. The ratio of coefficient of transmissibility and coefficient of permeability, is equal to the depth of acquifer through which water flows.
Answer: D

36. If the viscosity of ground water is 1.00, the Slitcher’s constant is 400, the effective size of soil particles in acquifer is 0.5 mm and hydraulic gradient is 1 in 80, the velocity of flow is

A. 0.25 m/day
B. 0.50 m/day
C. 0.75 m/day
D. 1.00 m/day
E. 1.25 m/day.
Answer: E

37. Shrouding is provided in

A. cavity type tube wells
B. slotted type tube wells
C. strainer type tube wells
D. perforated type tube wells.
Answer: B

38. The efficiency of a pump may be taken as

A. 0.55
B. 0.60
C. 0.65
D. 0.70
Answer: C

39. Pick up the correct statement from the following :

A. Perched aquifer is found in unconfined aquifer
B. The top surface of the water held in the perched aquifer, is known as perched water table
C. Perched aquifer is formed in unfined accquifer if an impervious layer exists
D. All the above.
Answer: D

40. Consumptive use of a crop during growth, is the amount of

A. interception
B. transpiration
C. evaporation
D. all the above.
Answer: D

41. For calculating the evaporation rate over a reservoir surface E = 0.771 (1.465 – 0.00732 B) (0.44 – 0.007375 V) (pe – pa), the equation is given by

A. Roohwer’s, formula in M.K.S.
B. Roohwer’s formula in F.P.S.
C. Dalton’s formula in F.P.S.
D. Dalton’s formula in M.K.S.
Answer: A

42. For the estimate of high floods in fan-shaped catchment, the formula used is

A. Dicken’s formula
B. Ryve’s formula
C. Inglis formula
D. none of these.
Answer: C

43. In nature water may occur as

A. liquid
B. solid
C. vapours
D. all the above.
Answer: D

44. Hydrology is the science which deals with

A. rain water
B. river water
C. sea water
D. surface and underground water
E. flood water.
Answer: D

45. The surface run off is due to

A. initial rain
B. residual rain
C. rain in the net supply interval
D. all the above.
Answer: C

46. Hydrograph is a graphical representation of

A. surface run off
B. ground water flow
C. rain fall
D. discharge flowing in the river
E. none of these.
Answer: D

47. The infiltration capacity during rain storm, is considerably reduced due to

A. surface detention
B. soil moisture
C. compaction due to rain
D. washing of fine particles
E. all the above.
Answer: E

48. Rain simulators are used for the determination of

A. evaporation
B. precipitation
C. run off
D. infiltration capacity
E. none of these.
Answer: D

49. Precipitation includes

A. rain
B. snow
C. hail
D. all of these.
Answer: D

50. Pick up the correct statement from the following :

A. Central portion of a cyclone acts as a chimney through which air gets lifted
B. Cyclonic precipitation caused by a warm front is generally continuous
C. Convective precipitation generally occurs in the form of showers of high intensity in short duration
D. Greatest amount of orographic precipitation falls in the windward side of the barrier
E. All the above.
Answer: E

51. Non-recording rain gauges

A. collect the rain whose volume is measured by means of graduated cylinders
B. collect the rain which is directly measured by means of graduated cylinders in centimetres of water depth
C. are generally used in hilly terrain
D. are cylindrical in shape.
Answer: B

52. Indian Meteorological department uses the standard gauges whose collectors have apertures of

A. 50 or 100 sq. cm area
B. 100 or 150 sq. cm area
C. 100 or 200 sq. cm area
D. 250 or 500 sq. cm area.
Answer: C

53. The polythene bottles are used for collecting rain water and. their capacities is

A. 2 litres
B. 4 litres
C. 10 litres
D. all the above.
Answer: D

54. Symon’s rain gauge is

A. tipping-bucket gauge
B. weighing type gauge
C. float recording gauge
D. non-recording gauge.

 

55. The rainfall cycle period in India is taken as

A. 15 years
B. 20 years
C. 25 years
D. 30 years
E. 35 years.
Answer: E

56. Isohytes are the imaginary lines joining the points of equal

A. pressure
B. height
C. humidity
D. rainfall.
Answer: D

57. The rainfall at any place is described by

A. its intensity
B. its duration
C. its frequency
D. all the above.
Answer: D

58. Pick up the correct statement from the following :

A. The intensity of rain is the rate at which it falls
B. The duration of rain is the time for which it falls with a given intensity
C. The frequency of rain is the number of times, if falls
D. All the above.
Answer: D

59. Pick up the incorrect statement from the following :

A. At two meteorologically homogeneous stations, the average annual precipitation is same
B. If the average annual precipitation at two places is same these are meteorologically homogeneous stations
C. Neither (a) nor (b)
D. Both (a) and (b).
Answer: B

60. Pick up the correct statement from the following :

A. The throat of the section of a control meter is either rectangular or trapezoidal
B. The floor of the control meter throat is almost level
C. The floor of the expanding outlet of the control meter is given a steep slope
D. A properly designed control meter is associated with the phenomena of hydraulic jump
E. All the above.
Answer: E

61. Discharge curve may be extended by logarithmic method if

A. cross section of river is uniform
B. river is broader and shallower
C. river is of any type
D. none of these.
Answer: A

62.  The best instrument for measuring the velocity of a stream flow is

A. pitot tube
B. Price’s current meter
C. surface float
D. sub-surface float.
Answer: B

63. The average mean velocity of a stream having depth h, may be obtained by taking the average of the readings of a current meter at a depth of

A. 0.1 h and 0.9 h
B. 0.2 h and 0.8 h
C. 0.3 h and 0.7 h
D. 0.4 h and 0.6 h.
Answer: B

64. If the velocities of flow of a stream of 10 m depth recorded by a current meter at depths of 2 m and 8 m are 0.7 m and 0.3 m respectively, the discharge per unit width of the stream in cubic metres, is

A. 2
B. 3
C. 4
D. 5
E. 6
Answer: D

65. The time required by rain water to reach the outlet of drainage basin, is generally called

A. time of concentration
B. time of overland flow
C. concentration time of overland flow
D. duration of the rainfall
E. none of these.
Answer: A

66. Time of overland flow, is affected by

A. slope of the basin
B. type of the ground surface
C. length of the flow path
D. all the above.
Answer: D

67. A unit hydrograph is a hydrograph of a rain storm of a specified duration resulting from a run-off of

A. 15 mm
B. 20 mm
C. 25 mm
D. 30 mm.
Answer: B

68. Pick up the correct statement from the following :

A. The specified duration of unit hydrograph, is called unit duration
B. The rain during specified duration, is called unit storm
C. A unit hydrograph for a particular unit duration may be utilised for evaluating the run off hydrographs of other storms of like durations
D. The number of unit hydrographs for a given basin, is theoretically infinite
E. All the above.
Answer: E

69. The best unit period of a unit hydrograph, is equal to basin lag divided by

A. 2
B. 3
C. 4
D. 5
Answer: C

70. If total run off of a basin of 50 hectares is 0.8 cm, the ordinate of Bernard’s distribution graph, may be calculated by the formula (where Q is the discharge in cumecs at the given time)

A. y = 50 Q
B. y = 100 Q
C. y = 150 Q
D. y = 200 Q
E. y = 250 Q
Answer: E

71. Pick up the correct statement from the following :

A. The zone below water table, is called zone of saturation
B. The zone above water table, is called zone of aeration
C. The water which exists in the zone of saturation, is called ground water
D. Water in the zone of saturation, remains under hydrostatic pressure
E. All the above.
Answer: E

72. If the grain size of soil increases

A. surface area decreases
B. specific retention decreases
C. specific yield increases
D. water supply in well increases
E. all the above.
Answer: E

73. Pick up the correct statement from the following :

A. A confined bed of impervious material laid over an acquifer, is known as an aquiclude
B. The top most water bearing strata having no acquifer, is known as non-artesion acquifer
C. The ordinary gravity wells which supply water from the top most water bearing strata, are called water table wells
D. A permeable stratum which is capable to yield appreciate quantities of ground water, is known as an aquifer
E. All the above.
Answer: E

74. The Dupuit formula is based on

A. one observation well
B. two observation wells
C. three observation wells
D. no observation well
E. none of these.
Answer: D

75. A well is sunk in an unconfined aquifer having a saturated depth of 100 m. Assuming the equilibrium flow conditions and a homogeneous aquifer and radius of influence to be same, the ratio of discharges at 20 m and 40 m draw downs, is

A. 2/3
B. 5/4
C. 4/5
D. 7/8
E. 8/7
Answer: E

76. Evaporation losses depend upon

A. area of the water surface and depth of the water
B. nature of precipitation and type of vegetation
C. humidity and wind velocity
D. atmospheric temperature
E. all the above.
Answer: E

77. Phytometer method is generally used for the measurement of

A. interception
B. evaporation
C. transpiration
D. none of these.
Answer: C

78. For predicting floods of a given frequency, the best reliable method is

A. Unit hydrograph method
B. Gumbel’s analytical method
C. California method
D. None of these.
Answer: A

79. The earthen embankments constructed parallel to the river banks at some suitable distance for flood control, are known as

A. floods walls
B. river walls
C. levees
D. dikes
E. both (c) and (d).
Answer: E

80. Water is useful for

A. running hydroelectric turbines
B. floating the boats and ships
C. providing steam for running locomotives
D. warming dwelling units
E. all the above.
Answer: E

81. Knowledge of hydrology is necessary for civil engineers for

A. designing and construction of irrigation structures
B. designing and construction of bridges and culverts
C. flood control works
D. all the above.
Answer: D

82. Pick up the correct statement from the following :

A. Run off and surface run off are the same
B. Run off includes the water flowing over the surface
C. Run off is sometimes called discharge of the river
D. Surface run off is sometimes called stream flow.
Answer: C

83. Pick up the correct statement from the following :

A. Yield of a drainage basin is the run off at any time
B. Yield of a drainage basin is the run off over long periods
C. Yield of a drainage basin is expressed as surface run off per year
D. Run off is expressed as total volume per day
E. None of these.
Answer: B

84. Run off includes

A. precipitation over catchment area of the stream and its attributaries
B. surface run off
C. ground water flow
D. all the above.
Answer: D

85. Pick up the correct statement from the following :

A. Hydrograph is a plot of discharge and time
B. In hydrographs, time is plotted on X-axis
C. The maximum flow in the river due to rainfall, is called peak flow
D. Peak flows are different for rainfalls
E. All the above.
Answer: E

86. A soil strata may consist of

A. soil zone
B. intermediate zone
C. capillary zone
D. ground water zone
E. all the above.
Answer: E

87. Pick up the correct statement from the following :

A. The amount of water retained on the surface of soil grains by molecular attraction, is known as pellicular water
B. The degree of resistance to movement of the pellicular water generally expressed by the surface tension
C. The pellicular water held in any soil, is called field capacity
D. The portion of the pellicular water absorbed by the root action of the vegetation, is called available moisture
E. All the above.
Answer: E

88. Pick up the correct statement from the following :

A. If ground water enters the channel, the channel is known as effulent channel
B. If water goes out of channel to meet ground water, the channel is said to be influent stream
C. If the water table is at higher level than the water level in channel, ground water flows to the stream
D. If the water level in stream is higher than the water table level, water from the channel enters into ground water
E. All the above.
Answer: E

89. Pressure exerted by fully saturated air, is known

A. partial pressure
B. vapour pressure
C. saturation vapour pressure
D. saturation pressure
E. (c) and (d) of the above.
Answer: E

90. A volume of air at constant barometric pressure may be brought to dew point by

A. increasing the temperature
B. decreasing the temperature
C. neither (a) nor (b)
D. both (a) and (b).
Answer: B

91. If the dew point is greater than 0°C

A. dew will be formed
B. frost will be formed
C. vapours will be formed
D. neither of these.
Answer: A

92. Humidity refers to

A. temperature of the air
B. pressure of the air
C. moisture content of the air
D. volume of the air.
Answer: C

93. Relative humidity is the ratio of actual vapour pressure to the saturation vapour pressure

A. at the same temperature
B. at the same pressure
C. in the same volume
D. in the atmosphere.
Answer: A

94. Pick up correct statement from the following :

A. The air from outer portion of cyclones gets lifted for causing precipitation
B. The air from central portion of cyclone’s gets lifted for causing precipitation
C. The air from entire surface of the cyclones gets lifted for causing precipitation
D. None of those.
Answer: B

95. Precipitation caused due to upward movement of warmer air as compared to surrounding air, is called

A. cyclonic precipitation
B. convective precipitation
C. orographic precipitation
D. none of these.
Answer: B

96. Precipitation caused due to striking of air masses with a topographical feature, is called

A. orographic precipitation
B. convective precipitation
C. cyclonic precipitation
D. none of these.
Answer: A

97. The specifications of most commonly used standard gauges in India, are

A. 200 sq. cm collector and 4 litres bottle
B. 100 sq. cm collector and 2 litres bottle
C. 200 sq. cm collector and 10 litres bottle
D. 100 sq. cm collector and 4 litres bottle.
Answer: A

98. The recurrence interval (R.I.) of 20 cm rain storm at a place is 5 years.

A. The place will definitely have 20 cm rain storm after every five years
B. The place may have 20 cm rain storm after every five years
C. The place may have 20 cm rain storm within a set of 5 years twice
D. None of these.
Answer: B

99. Sharp crested weirs are generally used

A. for large flows
B. for small flows
C. for streams carrying high sediment loads
D. for rivers carrying floating debris
E. none of these.
Answer: A

100. Pick up the correct statement from the following :

A. Higher the gauge, more deficient will be the rain catch
B. Heavier the rain, lesser will be the rain catch
C. The trees serving as wind brakes in the vicinity of the gauge, should not subtend angles greater than 45°
D. Coniferrous forest is idealy suited for installing the gauge
E. All the above.
Answer: E

101. The respective storm totals at three surrounding stations A, B and C are 110, 90 and 70 mm. If the normal annual precipitation amounts at stations X, A, B and C are respectively 1000, 1100, 1200 and 1250 mm, the estimated storm precipitation at X is

A. 75 mm
B. 77 mm
C. 79 mm
D. 81 mm.
Answer: B

102. For efficient working of a control meter, its throat length is approximately kept

A. equal to the critical depth
B. twice the critical depth
C. three times the critical depth
D. four times the critical depth.
Answer: C

103. A control meter is preferred to a weir because

A. it measures the discharge even in silt laiden streams
B. the velocity of approach of the channel increases above the control, and thus removes the silt completely
C. it is not damaged by floating debris
D. all the above.
Answer: D

104. A river is said to be of uniform section if in its section

A. a segment of a circle can be fitted
B. a parabolic section can be fitted
C. a rectangular section can be fitted
D. a trapezoidal section can be fitted
E. all the above.
Answer: E

105. The run off is affected by

A. size of the basin
B. shape of the basin
C. elevation of the water shed
D. all the above.
Answer: D

106. The form factor of a drainage basin is obtained by dividing

A. area of the basin by the axial length
B. average width of the basin by the axial basin
C. area of the basin by the square of the axial length
D. both (a) an (b)
E. both (b) and (c).
Answer: E

107. The area of a drainage basin whose axial length is 100 km is 2500 sq. km. Its form factor is

A. 0.10
B. 0.20
C. 0.25
D. 0.30
E. 0.35
Answer: C

108. If the axial length of a drainage basin is 35 km and its form factor is 0.2, the total area of the basin is

A. 205 sq. km.
B. 215 sq. km.
C. 225 sq. km.
D. 235 sq. km.
E. 245 sq. km.
Answer: E

109. Run off is measured in

A. cubic metres
B. cubic metres per sec.
C. cubic metres per minute
D. cubic metres per hour.
Answer: B

110. Pick up the correct statement from the following :

A. The unit hydrograph of a specified unit duration obtained from the past data can be used to obtain the hydrograph of future storms of like duration
B. To obtain the ordinates of storm hydrograph, the ordinates of unit hydrograph are multiplied by the multiplying factor
C. The multiplying factor for storm hydrograph may be obtained by dividing the run off in mm by 25 mm
D. A tolerance of about 25% of specified duration of unit hydrograph may be accepted without any serious error
E. All the above.
Answer: E

111. Bernard’s distribution graph is a plot of time on X-axis and

A. run off on the y-axis
B. total run off on the y-axis
C. percentage of total surface run off on y-axis
D. percentage of total surface run off during uniform time intervals on y-axis
E. none of these.
Answer: D

112. An intense rain is falling at a uniform rate of 7.5 cm/hour for a period of 60 minutes on a basin whose areas is 500 hectares. If the average infiltration capacity during the entire rain period is assumed to be 1.5 cm/hr, the maximum run-off rate based on 10 minute peak percentage of 16% from distributing graph of the basin, is

A. 40 cumecs
B. 60 cumecs
C. 80 cumecs
D. 100 cumecs.
Answer: C

Explanation:

113. Pick up the correct statement from the following :

A. The ratio of total volume of voids in soil aggregates to the total volume of aggregate, is called Porosity
B. Water retained by the interstices due to molecular attraction, is called pellicular water
C. The ratio of volume of water obtained by gravity drainage to the total volume of the materials drained, is called ‘yield’
D. Sum of the percentage of specific yield and specific retention is 100
E. All the above.
Answer: E

114. The radius of influence is

A. radius of the main well
B. distance from the wall of main well to the point of zero draw down
C. distance from the centre of main well to the point of zero draw down
D. none of these.
Answer: C

115. When a constant discharge 2.91 litres/sec. was obtained in a pumping test, the draw downs in the test wells at 3 m and 6.184 m were 2.6 m and 0.3 m respectively. If over-all depth of the pumping well was 16 m, the permeability of the soil, is

A. 0.0005 cm/sec
B. 0.001 cm/sec
C. 0.002 cm/sec
D. 0.01 cm/sec.
Answer: B

116. Isopiastic lines are the contours

A. drawn to represent water table
B. drawn to represent piezometric heads
C. drawn to piezometric surface
D. none of these.
Answer: C

117. If h is the loss due to friction in a pipe. Total losses in strainer and bends may be taken as

A. 0.01 h
B. 0.45 h
C. 0.20 h
D. 0.25 h
E. 0.3 h.
Answer: D

118. The rate of evaporation from reservoirs may be determined by

A. pan-measurement method
B. empirical formulae
C. storage equation method
D. energy budget method
E. all the above.
Answer: E

119. In estimating the rate of evaporation from the reservoir surface, a pan 1.5 metres in diameter, was filled upto 8.0 cm. During a specified period of time, the rainfall  recorded was 5 cm. 3 cm of water was removed from the pan to keep the depth of water. At the end of the time, the depth was 9 cm. If the pan coefficient is 0.6, the evaporation loss is

A. 2 mm
B. 4 mm
C. 6 mm
D. 6 mm.
Answer: C

120. Dicken’s formula for high flood estimate, is useful only for the catchments in

A. Southern India
B. Northern India
C. Eastern India
D. Western India.
Answer: B

121. Levees and flood walls,

A. are designed to carry unbalanced water load
B. are designed with adequate dimensions
C. are means of controlling floods
D. are never provided free-boards.
Answer: D

122. If the diameter of sewer is 225 mm, the gradient required for generating self cleansing velocity, is

A. 1 in 60
B. 1 in 100
C. 1 in 120
D. none of these.
Answer: C

123. Pick up the correct statement from the following :

A. pH value indicates acidity and alkalinity of sewage
B. In acidic sewage, the pH value is less than 7
C. In alkaline sewage, the pH value is more than 7
D. Fresh sewage is generally alkaline
E. All the above.
Answer: E

124. The non-clog pump which permits solid matter to pass out with the liquid sewage, is

A. centrifugal pump
B. reciprocating pump
C. pneumatic ejector
D. none of these.
Answer: A

125. Assertion (A) : Discharging the effluents from the oxidation ponds just up stream of lakes or reservoirs is undesirable.

Reason (R) : The discharged algae get settled in the reservoirs and cause anaerobic decomposition and other water qualities.

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.
Answer: A

126. The width of a rectangular sewer is twice its depth while discharging 1.5 m/sec. The width of the sewer is

A. 0.68 m
B. 0.88 m
C. 1.36 m
D. 1.76 m.
Answer: C

127. Pick up the correct statement from the following :

A. In treated sewage, 4 PPm of D.O. is essential
B. Only very fresh sewage contains some dissolved oxygen
C. The solubility of oxygen in sewage is 95% that is in distilled water
D. All the above.
Answer: D

128. In olden days the type of section adopted in trunk and out fall sewers was

A. parabolic shaped
B. horse shoe shaped
C. egg shaped
D. circular shaped.
Answer: B

129. For the survival of fish in a river stream, the minimum dissolved oxygen is prescribed

A. 3 PPm
B. 4 PPm
C. 5 PPm
D. 10 ppm.
Answer: B

130. In a fully mechanised composting plant, involves

A. mechanized receipt
B. mechanized segregation
C. mechanized pulverising of refuse
D. all of these.
Answer: D

131. 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.
Answer: C

132. 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

A. 2 hours
B. 3 hours
C. 4 hours
D. 5 hours.
Answer: C

 

133. An inverted siphon is designed generally for

A. one pipe
B. two pipes
C. three pipes
D. four pipes.
Answer: C

134. A rainfall may be classified as acidic if its pH value is less or equal to

A. 6
B. 7
C. 5
D. 6.5
Answer: C

135. When drainage to sewage ratio is 20, the peak dry weather flow is

A. 20% of the design discharge
B. slightly less than 5% of the design discharge
C. slightly more than 5% of the design discharge
D. none of these.
Answer: B

136. 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.
Answer: A

137. 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

A. 204 cu m
B. 208 cu m
C. 212 cu m
D. 216 cu m
E. 220 cu m.
Answer: D

138. 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.

139. In primary sedimentation, the 0.2 mm inorganic solids get separated if specific gravity is

A. 2.25
B. 2.50
C. 2.55
D. 2.65
E. 2.75
Answer: D

140. 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.
Answer: C

141. Clogging of sewers, is caused due to

A. silting
B. low discharge
C. greasy and oily matters
D. domestic wastes thrown in manholes
E. all the above.
Answer: E

142. A sewer pipe contains 1 mm sand particles of specific gravity 2.65 and 5 mm organic particles of specific gravity 1.2, the minimum velocity required for removing the sewerage, is

A. 0.30 m/sec
B. 0.35 m/sec
C. 0.40 m/sec
D. 0.45 m/sec
E. 0.50 m/sec.
Answer: D

143. The coagulant widely used for sewage treatment, is

A. alum
B. ferric chloride
C. ferric sulphate
D. chlorinated copperas.

144. House connections to the laterals is generally made by

A. R.C.C.
B. P.C.C.
C. Cast iron
D. Glazed stonewares.
Answer: D

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

A. 1.5
B. 2.0
C. 3.0
D. 4.0
Answer: B

146. Dilution method of disposing off sewage, is not preferred to

A. when sewage is fresh
B. when diluting water has high dissolved oxygen content
C. when diluting water is used for water supply near the point of sewage disposed
D. when the diluting water is having flow currents
E. none of these.
Answer: C

147. For house drainage minimum gradient is

A. 1 in 60
B. 1 in 80
C. 1 in 10
D. 1 in 400
Answer: A

 

148. 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.
Answer: D

149. The ratio of minimum hourly flow to the average flow of sewage is

A. 1/4
B. 1/3
C. 1/2
D. 3/4
Answer: B

150. Bio-chemical oxygen demand (BOD) for the first 20 days in generally referred to

A. initial demand
B. first stage demand
C. carbonaceous demand
D. all of these.
Answer: D

151. Flocculated particles do not change their

A. size
B. shape
C. weight
D. none of these.
Answer: D

152. For non-scouring velocity 5 m/sec, the type of sewers generally preferred to, is

A. cast iron sewers
B. cement concrete sewers
C. glazed bricks sewers
D. stone ware sewers.
Answer: C

153. Disposal to sewage in large cities, is done in

A. irrigation
B. dilution
C. oxidation
D. putrifaction.
Answer: B

154. In R.C. sewer pipes, the percentage longitudinal reinforcement to the cross-sectional area of concrete is kept

A. 10.0
B. 5.0
C. 2.0
D. 0.25
Answer: D
155. For the COD test of sewage, organic matter is oxidised by K2Cr207 in the presence of

A. H2SO4
B. HNO3
C. HCl
D. none of these.
Answer: A

156. The asbestos cement pipes are generally laid

A. horizontally
B. vertically
C. at an angle of 30°
D. at an angle of 60°.
Answer: B

157. Chlorination of water is done for the removal of

A. bacterias
B. suspended solids
C. sediments
D. hardness.
Answer: A

158. For evaporation and measurement of settlable solids, the apparatus used, is

A. a jar
B. a breaker
C. a test tube
D. an Imhoff cone.
Answer: D

159. In SI units the power of sound is represented in

A. kgs
B. joules
C. neutons
D. watts.
Answer: D

160. A rain sanitary sewer is constructed to carry

A. sanitary sewage
B. storm sewage
C. surface water
D. ground water
E. all the above.
Answer: A

161. The sewage is pumped up

A. from low lying areas
B. from flat areas
C. from basements
D. across a high ridge
E. all the above.
Answer: E

162. Removal of oil and grease from sewage, is known

A. screening
B. skimming
C. filtration
D. none of these.
Answer: B

163. The gas which may cause explosion in sewers, is

A. carbondioxide
B. methane
C. ammonia
D. carbon monoxide.
Answer: B

164. In sewers the effect of scouring is more on

A. top side
B. bottom side
C. horizontal side
D. all sides.
Answer: B

165. 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 20°C, B.O.D. of the sewage is

A. 50 mg/l
B. 100 mg/l
C. 150 mg/l
D. 200 mg/l
E. 250 mg/l.
Answer: E

166. 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.
Answer: D

167. Rate of flow of sewage is generally assumed

A. more than the rate of water supply
B. equal to the rate of water supply
C. less than the rate of water supply
D. at 150 litres per capita.
Answer: C

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

A. with beds of rocks and gravels
B. lined with stones
C. both (a) and (b)
D. neither (a) nor (b).
Answer: C

169. The digested sludge from septic tanks, is removed after a maximum period of

A. 3 years
B. 3.5 years
C. 4 years
D. 5 years.
Answer: A

170. For providing an Indian type W.C., the R.C.C. slabs in the toilet portion

A. should be sunk by 20 cm
B. should be kept 20 cm above the adjacent portion
C. should be sunk by 50 cm
D. need not be sunk.
Answer: C

171. The gradient of sewers depends upon

A. velocity of flow
B. diameter of the sewer
C. discharge
D. all the above.
Answer: D

172. 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
E. 3 hours.
Answer: D

173. The drop man holes are generally provided in sewers for

A. industrial areas
B. large town ships
C. hilly town ships
D. cities in plains.
Answer: C

174. Sewer ventilating columns are generally placed at

A. distances 150 m to 300 m
B. upper ends of branch sewers
C. every change in the size of sewers
D. all the above.
Answer: D

175. In case of Imhoff tanks,

A. the shape is rectangular
B. detention period is 2 hours
C. the velocity of flow is restricted to 0.30 m/minute
D. surface loading is limited to 30, 000 litres/m of plan area per day
E. All the above.
Answer: E

176. A drop manhole is provided if

A. a sewer drops from a height
B. a branch sewer joins the main sewer at higher level
C. a lamp is inserted to check obstruction
D. none of these.
Answer: B

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

A. 5
B. 10
C. 15
D. 20
Answer: D

178. Pick up the correct statement from the following :

A. Indore method of composting involves decomposition under aerobic conditions
B. Bangalore method of composting involves decomposing under anaerobic conditions
C. Fully stabilised refuse by the Bangalore method of compositing is a powdery mass called humus
D. all of these.
Answer: D

179. The liquid wastes from kitchens, bath rooms and wash basins, is not called

A. liquid waste
B. sullage
C. sewage
D. none of these.
Answer: C

180. The presence of free ammonia in sewage, is detected by

A. boiling
B. adding pottassium permanganate
C. adding sulphuric acid
D. phenol-di-sulphuric acid.
Answer: A

181. 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.
Answer: B

182. The standard B.O.D. of water is taken for

A. 1 day
B. 2 days
C. 3 days
D. 5 days
E. 10 days.
Answer: D

183. To prevent settling down of sewage both at the bottom and on the sides of a large sewer, self-cleaning 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
E. 1.0 m/sec.
Answer: D

184. Pick up the correct statement from the following :

A. Turbidity is more in strong sewage
B. The black colour indicates septic sewage
C. The fresh sewage is practically odourless
D. The sewage omits offensive odours after four hours
E. All the above.
Answer: E

185. A sewer running partially full and hurried with back filled, fails in compression due to

A. weight of the pipe
B. weight of the back fill
C. superimposed traffic loads
D. all the above.
Answer: D

Explanation:

186. 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
E. 1.2 to 1.50 m.
Answer: C

187. For design purposes, the normal rate of infiltration of ground water into the sewer, is

A. 500 litres/km/cm
B. 1000 litres/km/cm
C. 1500 litres/km/cm
D. 2000 litres/km/cm
E. 2500 litres/km/cm.
Answer: D

188. The effluent of a septic tank is

A. fit for discharge into any open drain
B. foul and contains dissolved and suspended solids
C. as good as that from a complete treatment
D. none of these.
Answer: A

189. 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.
Answer: A

190. Fresh sewage may become stale in

A. one hour
B. two to three hours
C. three to four hours
D. six hours.
E. ten hours.
Answer: C

191. The small sewers are cleaned by

A. flushing
B. cane rodding
C. wooden pills
D. none of these.
Answer: A

192. Dry water flow in a combined sewer, is

A. industrial sewage
B. domestic sewage
C. storm water
D. inclusive of domestic and industrial sewage but excludes storm water.
Answer: D

193. Which one of the following tests is used for testing sewer pipes :

A. water test
B. ball test
C. mirror test
D. all of these.
Answer: D

194. 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
E. None of these.
Answer: A

195. 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.
Answer: A

196. In sewage having fully oxidised organic matter, the nitrogen exists in the form of

A. nitrites
B. nitrates
C. free ammonia
D. aluminoid nitrogen
E. none of these.
Answer: B

197. It is customary to design a sewer for D.W.F. on the basis of

A. average demand
B. twice the average demand
C. thrice the average demand
D. four times the average demand.
Answer: C

198. 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.
Answer: D

199. Pick up the correct statement from the following :

A. The larger the sewer in size, more will be velocity
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.
Answer: D

200. In septic tanks,

A. free board of 0.3 m may be provided
B. the baffles or tees are extended up to top level of scum
C. the clear space between the baffle top and covering slab is about 7.5 cm
D. the inlet is kept 30 cm below the sewage line and outlet is kept at a level 40% depth of the sewage
E. all the above.
Answer: E

201. The sewer pipe which carries sewage from a building for immediate disposal is

A. house sewer
B. lateral sewer
C. intercepting sewer
D. main sewer.
Answer: A

202. The algae dies out in the zone of

A. degradation
B. active decomposition
C. recovery
D. cleaner water.

203. The recommended detention period for grit chambers is

A. 1 minute
B. 2 minutes
C. 3 minutes
D. 5 minutes.
Answer: A

204. Pick up the correct statement from the following :

A. The materials separated by screens, is called screenings
B. The screenings are disposed off either by burning or by burial or by dumping
C. The process of burning the screenings, is called incineration
D. The process of burning the screenings, is known as compositing
E. All the above.
Answer: E

205. In septic tanks,

A. free board of 0.3 m may be provided
B. the baffles or tees are extended up to top level of scum
C. the clear space between the baffle top and covering slab is about 7.5 cm
D. the inlet is kept 30 cm below the sewage line and outlet is kept at a level 40% depth of the sewage
E. all the above.
Answer: E

206. The sewer pipe which carries sewage from a building for immediate disposal is

A. house sewer
B. lateral sewer
C. intercepting sewer
D. main sewer.
Answer: A

207. The algae dies out in the zone of

A. degradation
B. active decomposition
C. recovery
D. cleaner water.

208. The recommended detention period for grit chambers is

A. 1 minute
B. 2 minutes
C. 3 minutes
D. 5 minutes.
Answer: A

209. Pick up the correct statement from the following :

A. The materials separated by screens, is called screenings
B. The screenings are disposed off either by burning or by burial or by dumping
C. The process of burning the screenings, is called incineration
D. The process of burning the screenings, is known as compositing
E. All the above.
Answer: E

210. The pH value of fresh sewage is usually

A. equal to 7
B. more than 7
C. less than 7
D. equal to zero.
Answer: B

211. The moisture content of a sludge is reduced from 90% to 80% in a sludge digestion tank. The percentage decrease in the volume of sludge, is

A. 25%
B. 50%
C. 10%
D. 5%.
Answer: B

212. 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.
Answer: D

213. The factor responsible for purification of sewage in river is

A. Hydrology
B. Dissolved oxygen in water
C. Temperature
D. Turbulence
E. All the above.
Answer: E

214. If the peak discharge of a storm water drain (S.W. Drain) is e.xpected to exceed 150 cumecs, the free board to be provided, is

A. 100 cm
B. 90 cm
C. 80 cm
D. 50 cm.
Answer: A

215. 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.
Answer: A

216. Depletion of ozone layer in the outer atmosphere may cause

A. lung cancer
B. skin cancer
C. bronchitis
D. heart disorder.
Answer: B

217. The spacing of bars of perforations of fine screens used for the treatment of sewage, is

A. 2 to 3 mm
B. 3 to 5 mm
C. 5 to 8 mm
D. 8 to 10 mm.
Answer: A

 

218. 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.
Answer: A

219. Ventilating shafts are provided to a sewer line at every

A. 100 m
B. 150 m
C. 200 m
D. 300 m
E. 500 m.
Answer: D

220. Which one of the following part of human body withstands minimum radiation

A. thyroid
B. kidneys
C. eyes
D. ovaries/testis.
Answer: D

 

221. The water carried sewerage system removes

A. domestic sewage
B. industrial sewage
C. storm sewage
D. all the above.
Answer: D

222. Stoneware sewers are available in size

A. 10 cm
B. 15 cm
C. 20 cm
D. 25 cm
E. all the above.
Answer: E

223. The sludge does not contain waste water from

A. bath rooms
B. wash basins
C. kitchen sinks
D. toilets.
Answer: D

224. The maximum diameter of sewers adopted in the designs is

A. 1.0 m
B. 2.0 m
C. 3.0 m
D. 4.0 m.
Answer: C

225. Sluge banks are formed if sewage is disposed of in

A. rivers
B. seas
C. lakes
D. none of these.
Answer: B

226. Design period of 40 to 50 years is adopted for

A. branch sewers
B. main sewers
C. trunk sewers
D. all the above.
Answer: D

227. The pH value of sewage is determined with the help of

A. Imhoff Cone
B. turbidimeter
C. potentiometer
D. none of these.
Answer: C

228. Lead caulked joints are used for laying

A. stone ware pipes
B. earthern ware pipes
C. C.I. pipes
D. G.I. pipes.
Answer: B

229. Pick up the correct statement from the following :

A. The water supply pipes carry pure water free from solid particles
B. The water supply pipes get clogged if flow velocity is less than self cleansing velocity
C. The sewers may be carried up and down the hills and valleys
D. The sewer pipes are generally laid along level hills
E. None of these.
Answer: A

230. For trunk sewers more than 1.25 m in diameter, the ratio of the maximum daily sewage flow to the average daily sewage flow is assumed

A. 1.5
B. 2.0
C. 2.5
D. 3.0
E. 3.5
Answer: A

231. 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.
Answer: D

232. Primary treatment of sewage consists of removal of

A. large suspended organic solids
B. oil and grease
C. sand and girt
D. floating materials
E. none of these.
Answer: A

233. The rainfall at any place may be determined by

A. its intensity
B. its direction
C. its frequency
D. all the above.
Answer: D

234. 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%
E. 95%.
Answer: C

235. Which one of the following gases is most significant as air pollutant

A. Carbondioxide
B. Oxygen
C. Nitrogen
D. Sulphurdioxide.
Answer: D

236. 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.
Answer: D

237. 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.
Answer: B

238. The maximum spacing of manholes specified by Indian standard in sewers upto 0.3 m diameter is

A. 20 m
B. 30 m
C. 45 m
D. 75 m.
Answer: C

239. The design period in years for pumping plants, is

A. 1
B. 2 to 3
C. 3 to 5
D. 5 to 10
Answer: D

240. A five day B.O.D. at 15°C of the sewage of a town is 100 kg/day. If the 5 day B.O.D. per head at 15°C for standard sewage is 0.1 kg/day, the population equivalent is

A. 100
B. 1000
C. 5000
D. 10000
Answer: D

241. 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

A. 0.05552 cumec
B. 0.05554 cumec
C. 0.05556 cumec
D. 0.0556 cumec
E. 0.0558 cumec.
Answer: C

242. If the diameter of a sewer is 150 mm, the gradient required for generating self cleansing velocity, is

A. 1 in 60
B. 1 in 100
C. 1 in 120
D. none of these.
Answer: B

243. The average temperature of sewage in India, is

A. 10°C
B. 15°C
C. 20°C
D. 25°C
E. 30°C.
Answer: C

244. The most widely used pump for lifting sewage is

A. centrifugal pump
B. reciprocating pump
C. pneumatic ejector
D. air pressure pump.
Answer: A

245. The sewer which resists sulphide corrosion, is

A. Brick sewer
B. Cast iron sewer
C. R.C.C. sewer
D. Lead sewer
E. None of these.
Answer: D

246. For large sewers, maximum distance between manholes may be

A. 50 m
B. 100 m
C. 200 m
D. 300 m
E. 400 m.
Answer: D

247. The first stage of neutral process of sludge digestion, is

A. acid fermentation
B. acid regression
C. alkaline fermentation
D. none of these.
Answer: A

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

A. Methane gas
B. Hydrogen sulphide
C. Carbon dioxide gas
D. Diesel vapours.
Answer: B

249. Dried sewage after treatment is used as

A. fertilizer
B. building material
C. chemical for lowering B.O.D.
D. base material for paints.
Answer: A

250. The use of coarse screens for the disposal of sewage, may be dispensed with by

A. comminutor
B. shredder
C. both (a) and (b)
D. neither (a) nor (b).
Answer: C

251. Sewer pipes are designed for maximum discharge with 25% to 33% vacant cross-sectional area for

A. unexpected large scale infiltration of stream water
B. unexpected increase in the population
C. under estimates of maximum and average flows
D. All of the above.
Answer: D

252. Water content of sewage is about

A. 90%
B. 95%
C. 99.9%
D. 9.9%.
Answer: C

253. Imhoff cone is used to measure

A. total organic solids
B. total solids
C. total in organic solids
D. settleable solids.
Answer: D

254. For a grit chamber, if the recommended velocity of flow is 0.2 m/sec and detention period is 2 minutes, the length of the tank, is

A. 16 m
B. 20 m
C. 24 m
D. 30 m.
Answer: C

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

A. 100
B. 60
C. 40
D. 20
E. 10
Answer: D

256. Traps

A. are water seals which prevent the entry of foul gases
B. are used to trap the rats entering sewers
C. dissolve the foul gases
D. create syphonic action to increase the quick disposal of sewerage.
Answer: A

257. For estimating the peak run off the rational formula Q = 0.0278 KpA was evolved by

A. Kinchling
B. Lloyd Davis
C. Frubling
D. all the above.
Answer: D

258. Pick up the correct statement from the following :

A. Inlets are provided on the road surface at the lowest point for draining rain water
B. Inlets are generally provided at an interval of 30 m to 60 m along straight roads
C. Inlets having vertical openings, are called curb inlets
D. Inlets having horizontal openings, are called horizontal inlets
E. All the above.
Answer: E

259. Pick up the correct statement from the following :

A. The boning rod is used for checking the levels of the sewer inverts
B. Manhole covers are made circular for the convenience of the cleaning staff
C. A manhole is classified as deep manhole if its depth is more than 1.5 m
D. A manhole is classified as shallow manhole if its depth is. less than 0.9 m
E. All the above.
Answer: E

260. 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 20°C, the DO. concentration was 5 mg/l. The BOD of raw sewerage is

A. 100 mg/l
B. 200 mg/l
C. 300 mg/l
D. 400 mg/l.
Answer: C

261. 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.

262. The angle subtended by the surface of sewer water with partial flow, at sewer centre is 120°, the depth of sewerage is

A. 20 cm
B. 25 cm
C. 40 cm
D. 50 cm
E. 60 cm.
Answer: D

Explanation:

263. Imhoff cone is used to determine

A. settlable solids
B. suspended solids
C. dissolved solids
D. none of these.
Answer: A

264. The sewage discharge in a detritus tank of a treatment plant is 576 litres/sec with flow velocity of 0.2 m/sec. If the ratio of width to depth is 2, the depth is

A. 100 cm
B. 110 cm
C. 120 cm
D. 150 cm.
Answer: C

265. 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.
Answer: A

266. A well oxidized sewage contains nitrogen mainly as

A. nitrates
B. nitrites
C. free ammonia
D. none of these.
Answer: A

267. 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.
Answer: C

 

268. Assertion (A) : A free board of 0.3 m is provided above the top sewage line in septic tanks.

Reason (R) : It helps to accommodate the scum in the septic tank.

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.
Answer: A

269. Drop manholes at the junctions of sewer lines, are provided if

A. invert level of a branch sewer is more than 60 cm that of the main sewer
B. sewer line runs along a main road
C. ordinary manhole cannot be built
D. two sewer lines intersect.
Answer: A

 

270. Large diameter sewers subjected to external pressure alone, are reinforced

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
E. none of these.
Answer: D

271. Pick up the correct statement from the following :

A. The ratio of the quantity of the diluting water to that of the sewage, is known as dilution factor
B. The automatic purification of polluted water, is known self purification phenomenon
C. The photosynthesis is carried out in the presence of sun light
D. Grab sample is generally obtained from the surface where turbulence mixes the sewage particles
E. All the above.
Answer: E

272. In sewage, the solids in mg per litre is

A. 100 to 500
B. 500 to 1000
C. 1000 to 1500
D. 1500 to 2000
Answer: B

273. 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

A. 100 mm dia.
B. 150 mm dia.
C. 225 mm dia.
D. all of these.
Answer: C

274. 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.
Answer: D

275. During putrifaction process of sewage the gas given off, is

A. carbon dioxide
B. hydrogen
C. ammonia
D. methane
E. all the above.
Answer: E

276. A circular sewer section is preferred to because

A. it is cheaper in construction
B. it provides maximum area for a given perimeter
C. it provides maximum hydraulic mean depth
D. all the above.
Answer: D

277. 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.

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.
Answer: A

278. If the grit in grit chambers is 4.5 million litres per day, its cleaning is done

A. manually
B. mechanically
C. hydraulically
D. electrically.
Answer: A

279. The gas evolved in sewers is

A. Carbondioxide
B. Hydrogen sulphide
C. Methane
D. All of these.
Answer: D

280. The maximum depth of sedimentation tanks, is kept

A. 3 m
B. 3.5 m
C. 4 m
D. 4.5 m.
Answer: A

281. The reduced levels of the string at the consecutive sight rails A and B are 203.575 m, 203.475 m respectively. If the difference of their R.D.s is 10 m, the gradient of the sewer line is

A. 1 in 100 upward
B. 1 in 500 upward
C. 1 in 100 downward
D. 1 in 503 upward.
Answer: C

 

282. The detention time (t) of a settling tank, may be defined as the time required for

A. a particle to travel along its length
B. a particle to travel from top surface to bottom sludge zone
C. the flow of sewage to fill the tank
D. none of these.
Answer: C

283. Discrete or granular particles change their

A. size
B. shape
C. weight
D. none of these.
Answer: D

284. For a peak discharge of 0.0157 cumec, with a velocity of 0.9 m/sec, the diameter of the sewer main, is

A. 10 cm
B. 12 cm
C. 15 cm
D. 18 cm
E. 20 cm.
Answer: C

285. For design of sewers, percentage of sewage discharge is assumed

A. 65 to 70%
B. 70 to 75%
C. 75 to 80%
D. 85%.
Answer: C

286. 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.

287. The sewerage system originates from

A. house sewers
B. lateral sewers
C. branch sewers
D. main sewers
E. out fall sewers.
Answer: A

288. 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.
Answer: B

289. 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.
Answer: C

290. If a paper moistened with lead acetate for five minutes when placed in manhole turns black. The sewer certainly contains

A. Hydrogen sulphide
B. Carbon dioxide
C. Methane
D. Oxygen
E. None of these.
Answer: A

291. The design period of sewage treatment works in normally

A. 5 – 10 years
B. 15 – 20 years
C. 30 – 40 years
D. 40 – 50 years.
Answer: B

292. The porosity of sediments in sewer pipes, is usually taken as

A. 0.010
B. 0.011
C. 0.012
D. 0.013
E. 0.020
Answer: D

293. In septic tanks, decomposition of organic bacteria, is done by

A. anaerobic bacteria
B. aerobic bacteria
C. both types of bacterias
D. none of these.
Answer: A

294. The stone ware sewers

A. are used for carrying sewage and drainage from houses
B. are manufactured from clays and shales
C. after casting are dried and burnt at temperature 150°C, 700°C and 1200°C
D. are generally provided with a water proof cover by vaporising sodium chloride
E. all the above.
Answer: E

295. ‘Cowl’ is provided at

A. lower end of ventilating column
B. upper end of ventilating column
C. upper end of the manhole
D. first step in manhole.
Answer: B

296. The sewer which transports the sewage to the point of treatment, is called

A. house sewer
B. out-fall sewer
C. branch sewer
D. lateral
E. main sewer.
Answer: B

 

297. Kjedahl nitrogen is a mixture of

A. ammonia and nitrogen
B. nitrogen and organic nitrogen
C. organic nitrogen and ammonia
D. all the above.
Answer: D

298. For sewer mains of 0.5 to 1 m diameter, the ratio of maximum daily sewage flow to the average daily sewage flow is assumed

A. 1.5
B. 2.0
C. 2.5
D. 3.0
Answer: B

299. 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.
Answer: C

300. Pick up the correct statement from the following :

A. The circular section of sewers provides maximum hydraulic mean depth
B. The circular sewers are provided for separate sewerage system
C. The circular sewers work efficiently if the sections run at least half full
D. Two sewers of different shapes are said to be hydraulically equivalent if they discharge at the same rate while running full on the same grade
E. All the above.
Answer: E

301. You are asked to design sewer pipes of diameters 0.4 m to 0.9 m at maximum flow, you will assume the sewer flow running at

A. full depth
B. half full
C. two third full
D. three fourth full.
Answer: B

302. Sewer pipes need be checked for

A. minimum flow
B. maximum flow
C. both (a) and (b)
D. none of these.
Answer: C

303. If D.O. concentration falls down to zero in any natural drainage, it indicates the zone of

A. degradation
B. active decomposition
C. recovery
D. cleaner water
E. none of these.
Answer: B

304. The ratio of design discharge to the surface area of a sedimentation tank is called

A. surface loading
B. overflow rate
C. overflow velocity
D. all of these.
Answer: D

305. 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.
Answer: B

306. The minimum diameter of a sewer is kept

A. 10 cm
B. 15 cm
C. 20 cm
D. 25 cm
E. 30 cm.
Answer: B

307. The minimum diameter of sewer to be adopted is

A. 10 cm
B. 12.5 cm
C. 15 cm
D. 25 cm.
Answer: C

308. To test chemical oxygen demand (C.O.D.) of sewage, organic matter is oxidised by pottassium dichromate in the presence of

A. Hydrochloric acid
B. Sulphuric acid
C. Nitric acid
D. Citric acid.
Answer: B

309. The discharge per unit plan area of a sedimentation tank, is generally called

A. over flow rate
B. surface loading
C. over flow velocity
D. all the above.
Answer: D

310 For detecting the nitrites in the sewage, the matching colour may be developed by adding

A. Pottassium permanganate
B. Sulphuric acid and napthamine
C. Phenol-di-sulphuric acid pottassium hydroxide
D. None of these.
Answer: B

311. The suitable cross-section of sewers to carry combined flow, is

A. circular
B. egg shaped
C. rectangular
D. horse shoe shaped.
Answer: B

312. If the diameter of a sewer is 100 mm, the gradient required for generating self cleansing velocity, is

A. 1 in 60
B. 1 in 100
C. 1 in 120
D. none of these.
Answer: A

313. Stone ware pipes are

A. highly resistant to sulphide corrosion
B. highly impervious
C. hydraulically efficient because of their smooth interior surface
D. specially suited to pressure pipes
E. none of these.
Answer: D

314. 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.
Answer: A

315. 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.
Answer: A

316. With self cleansing velocity in sewers

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.
Answer: D

317. Aerobic activity is maximum

A. in freshly produced sewage
B. at sewer pipes
C. in sewer treatment plants
D. none of these.
Answer: A

318. 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.
Answer: D

319. Which one of the following resists hydrogen sulphide corrosion

A. R.C.C.
B. Glazed stone wares
C. Asbestos cement
D. Glazed ware.
Answer: D

320. The sewerage system consists of

A. house sewer
B. lateral sewer
C. branch sewer
D. main sewer
E. all of these.
Answer: E

321. Hume steel pipes are

A. steel pipes
B. R.C.C. pipes
C. steel shell coated from inside with cement mortar
D. steel shell coated from outside with cement mortar
E. both (c) and (d).
Answer: E

322. The laying of sewers is done with

A. magnetic compass
B. theodolite
C. level
D. clinometer
E. plane table.
Answer: C

323. The rational formula for peak drainage discharge, was evolved by

A. Fruhling
B. Lloyd David
C. Kuichling
D. All of these.
Answer: D

324. The sewage treatment in septic tanks is due to

A. anaerobic decomposition
B. aerobic decomposition
C. parasitic decomposition
D. none of these.
Answer: A

325. 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.
Answer: D

326. In 1000 kg of sewage, the total solids approximate

A. 0.5 to 1.0 kg
B. 1 kg to 2.0 kg
C. 5 kg to 7.5 kg
D. 7.5 kg to 10 kg.
Answer: A

327. Pathogens (or pathogentic bacterias) in water may cause

A. typhoid
B. cholera
C. dysentery
D. infectious hepatitis
E. all the above.
Answer: E

328. Sewer manholes are generally provided at

A. the change of gradient
B. the change of direction
C. the junctions of sewers
D. all of these.
Answer: D

329. Before discharging the foul sewage into rivers, it is generally treated by

A. screening
B. sedimentation
C. oxidation
D. sludge digestion and disinfection
E. all the above.
Answer: E

330. The settlement of a particle in sedimentation tank, is affected by

A. velocity of flow
B. viscosity of water
C. size and shape of solid
D. specific gravity of solid
E. all the above.
Answer: E

331. If the length of overland flow from the critical point to the mouth of drain is 13.58 km and difference in level between the critical point and drain mouth is 10 m, the inlet time is

A. 2 hours
B. 4 hours
C. 6 hours
D. 8 hours.
Answer: D

332. Oxidation process results in the formation of

A. carbon dioxide
B. nitrates
C. sulphates
D. all the above.
Answer: D

333. 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
E. none of these.
Answer: D

335. As compared to fresh river water, sea water contains oxygen

A. 10% less
B. 20% less
C. 10% more
D. 20% more.
Answer: B

336. In detritus tanks,

A. flow velocity is kept 0.09 m/sec
B. detention period is kept 3 to 4 minutes
C. organic and inorganic materials are separated
D. all the above.
Answer: D

337. The width of a settling tank with 2 hour detention period for treating sewage 378 cu m per hour, is

A. 5 m
B. 5.5 m
C. 6 m
D. 6.5 m
E. 7 m.
Answer: E

338. 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.
Answer: C

 

339. The settlement velocity of a solid (diameter 0.5 mm, specific gravity 1.75) in water having temperature 10°C, is

A. 213.5 cm/sec
B. 313.5 cm/sec
C. 413.5 cm/sec
D. 500 cm/sec.
Answer: B

340. Pick up the correct statement from the following :

A. anaerobic bacteria flourish in the absence of oxygen
B. aerobic bacteria flourish in the presence of oxygen
C. facultative bacteria flourish with or without oxygen
D. all the above.
Answer: D

341. Antisyphonage pipe is fitted

A. at the end of septic tanks
B. on manholes
C. with a W.C. trap
D. at the beginning of sewer line.
Answer: C

342. To maintain aerobic biological activity, the moisture content of the compost mass should be about

A. 45%
B. 50%
C. 55%
D. 60%.
Answer: C

343. 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.
Answer: B

344. 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. between 400 to 500
E. more than 500
Answer: E

345. R.M.O. expenses include

A. running expenses
B. maintenance expenses
C. operation expenses
D. all the above.
Answer: D

346. 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.
Answer: B

347. In normal conditions, the period for sludge digestion, is

A. 10 days
B. 20 days
C. 30 days
D. 60 days
E. 90 days.
Answer: C

348. 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
E. 1 in 25
Answer: B

349. 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. capacity of the tank for 24 hours, is kept equal to maximum daily flow of sewage
E. all the above.
Answer: E

350. The temperature affects the

A. biological activity of bacterias in sewage
B. solubility of gases in sewage
C. viscosity of sewage
D. all the above.
Answer: D

351. 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.
Answer: A

352. 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.
Answer: D

353. A cylindrical ejector having its height 2 m fills after every 10 minutes with a peak sewage discharge of 0.0157 cumec. The diameter of the ejector chamber, is

A. 2.30 m
B. 2.40 m
C. 2.45 m
D. 2.50 m.
Answer: C

354. 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.
Answer: B

355. The following is the physical characteristic of sewage

A. turbidity
B. colour
C. odour
D. temperature
E. all the above.
Answer: E

356. The normal value of over flow rates for plain primary sedimentation tanks, 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
E. none of these.
Answer: B

357. 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.
Answer: D

358. Bottom openings 15 cm x 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.
Answer: B

359. Faculative bacterias survive in

A. the presence of oxygen
B. the absence of oxygen
C. both cases (a) and (b)
D. neither (a) nor (b).
Answer: C

360. The ratio of maximum sewage flow to average sewage flow for trunk mains having diameters more than 1.25 m, is

A. 1.5
B. 2.0
C. 3.0
D. 4.0
Answer: A

361. 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.
Answer: D

362. If the pH value of sewage is 7

A. it is acidic
B. it is alkaline
C. it is neutral
D. none of these.
Answer: C

363. Pick up the incorrect statement from the following :

A. The mixture of water and waste products, is called sewage
B. The treated sewage effluents, are generally used for irrigating the crops
C. The process of collecting, treating and disposing off the sewage, is called sewerage
D. The old convergency system was definitely better than water carried sewerage system
E. None of these.
Answer: D

364. Pick up the correct statement from the following :

A. Hydrogen sulphide gas in excess, may cause corrosion of concrete sewers
B. 4 ppm of Dissolved Oxygen (D.O.) is ensured before discharging the treated sewage in river
C. Solubility of oxygen in sewage is 95% of that of distilled water
D. Dissolved oxygen content of sewage, may be determined by Winkler’s method
E. All the above.
Answer: E

 

365. Pick up the correct statement from the following :

A. Small sewers are cleaned by flushing
B. Medium sewers are cleaned by cane rodding
C. Medium sewers may be cleaned by pills
D. Large sewers are cleaned by removing the deposited materials
E. All the above.
Answer: E

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

A. 2.5 to 3.0 m/sec
B. 3.0 to 4.0 m/sec
C. 3.5 to 4.5 m/sec
D. 4.5 to 5.5 m/sec.
Answer: A

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

A. 2 days
B. 5 days
C. 7 days
D. 12 days
E. 14 days.
Answer: E

368. 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
E. 100 mm.
Answer: D

369. 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.
Answer: D

370. The layers of vegetable wastes and night soil alternatively piled above the ground to form a mound, is called

A. a heap
B. plateu
C. windrow
D. none of these.
Answer: D

371. If the discharge of a sewer running half is 628 1.p.s., i = 0.001, and n = 0.010, the diameter of the sewer, is

A. 1.39 m
B. 1.49 m
C. 1.59 m
D. 1.69 m
E. 1.79 m.
Answer: D

372. 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).
Answer: C

373. A manhole is generally provided at each

A. bend
B. junction
C. change of gradient
D. change of sewer diameter
E. all the above.
Answer: E

374. Pick up the correct statement from the following :

A. Rate of digestion of slugde is more at higher temperature
B. Thermophilic organisms digest the sludge if the temperature ranges from 40° to 60°C
C. Mesophilic organisms digest the sludge if the temperature is between 25° and 40°C
D. 90% of digestion takes place in 30 days at 29°C, the optimum mesophilic temperature
E. All the above.
Answer: E

375. The sewer which collects the discharge from a collecting system and delivers it to a treatment plant, is known

A. house sewer
B. lateral sewer
C. branch sewer
D. sewer outfall.
Answer: D

376. If the depletion of oxygen is found to be 5 ppm after incubating a 2.5% solution of sewage sample for 5 days at 21°C, B.O.D. of the sewage is

A. 50 ppm
B. 100 ppm
C. 150 ppm
D. 200 ppm
E. 250 ppm.
Answer: D

377. Setting out the alignments of sewers may start from

A. city
B. out-fall
C. tail end
D. any point.
Answer: C

378. 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
E. None of these.
Answer: C

379. The underground sewers are more subjected to

A. tensile force
B. compressive force
C. bending force
D. shearing force.
Answer: B

380. Pick up the correct statement from the following :

A. the sewer pipes of sizes less than 0.4 m diameter are designed as running full at maximum discharge
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. all the above.
Answer: D

381. 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.
Answer: D

382. The normal values of over flow rates for secondary sedimentation tanks, 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 10, 000 litres/sqm/day
E. none of these.
Answer: A

383. The Brake Horse power of the motor (efficiency 60%) required for a pump of capacity 0.075 cumec for a total lift of 12 m, is

A. 10
B. 15
C. 20
D. 25
Answer: C

384. 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.
Answer: B

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

A. Pottassium permanganate
B. Sulphuric acid and napthamine
C. Phenol-di-sulphuric acid and pottassium hydroxide
D. None of these.
Answer: C

386. 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 Bruge
C. William-Hazen
D. Kutter.
Answer: B

387. 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

A. 100 cm
B. 120 cm
C. 140 cm
D. 160 cm
E. 180 cm.
Answer: D

388. 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.
Answer: B

389. 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.
Answer: D

390. The most efficient cross section of sewers in a separate sewerage system is

A. parabolic
B. circular
C. rectangular
D. new egged.
Answer: B

391. If a 2% solution of sewage sample is incubated for 5 days at 20°C and the dissolved oxygen depletion was found to be 8 mg/l. The BOD of the sewage is

A. 100 mg/l
B. 200 mg/l
C. 300 mg/l
D. 400 mg/l.
Answer: D

Explanation:

392. 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.
Answer: D

393. The rate of accumulation of sludge per person per year, is

A. 10 litres
B. 15 litres
C. 20 litres
D. 25 litres
E. 30 litres.
Answer: C

394. The disintegrating pump in which solid matter is broken up before passing out, is

A. centrifugal pump
B. reciprocating pump
C. pneumatic ejector
D. none of these.
Answer: A

 

395. Pick up the incorrect statement from the following for allowing workers to enter sewers

A. The particular manhole and one manhole on up stream and one manhole on down stream should remain open for 30 minutes
B. Proper tests for the presence of poisonous gases must be carried out
C. The men entering the manhole should be advised to smoke in the sewer
D. Warning signals should be erected
E. None of these.
Answer: C

396. 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.
Answer: C

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

A. parabolic
B. circular
C. rectangular
D. new egged.
Answer: B

398. Pick up the incorrect size of stone ware sewers

A. 52.5 cm
B. 67.5 cm
C. 82.5 cm
D. 90 cm
E. none of these.
Answer: E

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

A. raising low lying areas by dumping
B. concreting
C. both (a) and (b)
D. neither (a) nor (b).
Answer: B

400. In a sludge tank, the gas mainly produced, is

A. Oxygen
B. Nitrogen
C. Hydrogen
D. Carbon dioxide
E. Methane.
Answer: E

401. The intensity of rain is expressed in

A. cm/minute
B. cm/hour
C. cm/day
D. none of these.
Answer: B

402. 1000 kg of sewage contains

A. 0.112 kg in suspension
B. 0.112 kg in solution
C. 0.225 kg in solution
D. 0.450 kg in suspension
E. both (a) and (c) of above.
Answer: E

403. The normal values of over flow rates for sedimentation tanks using coagulent, 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
E. none of these.
Answer: C