Environmental Engineering MCQs Practice Set
1. The length of rectangular sedimentation tank should not be more than (Where B is the width of the tank)
A) B
B) 2B
C) 4B
D) 8B
Ans. C
2. In water treatment, rapid gravity filters are adopted to remove
A) Dissolved organic substances
B) Dissolved solids and dissolved gases
C) Floating solids and dissolved in organic solids
D) Bacteria and colloidal solids
Ans. D
3. Disinfection of water results in
A) Removal of turbidity
B) Removal of hardness
C) Killing of disease bacteria
D) Complete sterilisation
Ans. C
4. The type of valve which is provided to control the flow of water in the distribution system at street corners and where the pipe lines intersect is
A) Check valve
B) Sluice valve
C) Safety valve
D) Scour valve
Ans. B
5. The design discharge for the separate sewer system shall be taken as
A) Equal to dry weather flow (DWF)
B) 2 x DWF
C) 3 x DWF
D) 6 x DWF
Ans. D
6. The most commonly used sewer under culverts is
A) Circular brick sewer
B) Circular cast iron sewer
C) Semi-elliptical sewer
D) Horseshoe type sewer
Ans. A
7. The relative stability of a sewage sample, whose dissolved oxygen is same as the to total oxygen required to satisfy BOD, is
A) 1
B) 100
C) Infinite
D) Zero
Ans. B
8. For satisfactory working of a sludge digestion unit, the pH range of digested sludge should be maintained as
A) 4.5 to 6.0
B) 6.5 to 8.0
C) 8.5 to 10.0
D) 10.5 to 12.0
Ans. B
9. As compared to geometrical increase method of forecasting population, arithmetical increase method gives
A) Lesser value
B) Higher value
C) Same value
D) Accurate value
Ans. A
10. The phenolic compounds in public water supply should not be more than
A) 0.1 ppm
B) 0.01 ppm
C) 0.001 ppm
D) 0.0001 ppm
Ans. C
11. Percentage of bacterial load that can be removed from water by the process of plain sedimentation is about
A) 10 to 25
B) 50
C) 75
D) 100
Ans. C
12. Double filtration is used
A) To increase the filtration slow sand filters capacity of
B) To increase the filtration rapid sand filters capacity of
C) For isolated building like pools, hotels etc swimming
D) All of the above
Ans. A
13. The major disadvantage of lime soda process of water softening is that
A) It is unsuitable for turbid and acidic water
B) Huge amount of precipitate is formed which creates a disposal problem
C) The effluent cannot be reduced to zero hardness
D) It is unsuitable for softening the water of excessive hardness
Ans. B
14. Scour valves are provided
A) At street corners to control the flow of water
B) At every depression and dead ends to drain out the waste water that may collect there
C) At the foot of rising main along the slope to prevent back running of water
D) At every summit of rising main s
Ans. B
15. The velocity of flow does not depend on
A) Grade of sewer
B) Length of sewer
C) Hydraulic mean depth of sewer
D) Roughness of sewer
Ans. B
16. The ratio of 5-day BOD to ultimate BOD is about
A) 43103
B) 43134
C) 43163
D) 1
Ans. B
17. Septic tank is a
(i) Settling tank
(ii) Digestion tank
(iii) Aeration tank
The correct answer is
A) Only (i)
B) (i) and (ii)
C) (i) and (iii)
D) Only (iii)
Ans. B
18. The population of a town in three consecutive years are 5000, 7000 and 8400 respectively. The population of the town in the fourth consecutive year according to geometrical increase method is
A) 9500
B) 9800
C) 10100
D) 10920
Ans. D
19. Which of the following values of pH represents a stronger acid?
A) 2
B) 5
C) 7
D) 10
Ans. A
20. The alum, when added as a coagulant in water
A) Does not require alkalinity in water for flocculation
B) Does not affect pH value of water
C) Increases pH value of water
D) Decreases pH value of water
Ans. D
21. Cleaning is done by
(i) Scraping and removal in filters slow sand
(ii) Back washing in slow sand filters
(iii) Scraping and removal in filters rapid sand
(iv) Backwashing in rapid sand filters
The correct answer is
A) (i) and (ii)
B) (ii) and (iii)
C) (i) and (iv)
D) (ii) and (iv)
Ans. C
22. As compared to cast iron pipes, steel pipes are
A) Heavier
B) Stronger
C) Costlier
D) Less susceptible to corrosion
Ans. B
23. The design discharge for the combined sewer system shall be taken as
A) Equal to rain fall
B) Rain fall + DWF
C) Rain fall + 2 DWF
D) Rain fall + 6 DWF
Ans. C
24. If Biochemical oxygen demand (BOD) of a town is 20000 kg/day and BOD per capita per day is 0.05 kg, then population equivalent of town is
A) 1000
B) 4000
C) 1,00,000
D) 4,00,000
Ans. D
25. The detention period for oxidation ponds is usually kept as
A) 48 hours
B) 24 hours
C) 10 to 15 days
D) 3 months
Ans. C
26. The devices which are installed for drawing water from the sources are called
A) Aquifers
B) Aquiclude
C) Filters
D) In takes
Ans. D
27. Residual chlorin e in water is determined by
A) Starch iodide method
B) Orthotolidine method
C) Both (A) and (B)
D) None of the above
Ans. C
28. The percentage of chlorin e in fresh bleaching powder is about
A) 10 to 15
B) 20 to 25
C) 30 to 35
D) 40 to 50
Ans. C
29. Sewerage system is usually designed for
A) 10 years
B) 25 years
C) 50 years
D) 75 years
Ans. B
30. The characteristics of fresh and septic sewage respectively are
A) Acidic and alkaline
B) Alkaline and acidic
C) Both acidic
D) Both alkaline
Ans. B
31. Which of the following unit works in anaerobic conditions?
A) Sludge digestion tank
B) Sedimentation tank
C) Activated sludge treatment
D) Trickling filters
Ans. A
32. As compared to shallow wells, deep wells have
A) More depth
B) Less depth
C) More discharge
D) Less discharge
Ans. C
33. The rate of filtration in slow sand filters in million litres per day per hectare is about
A) 50 to 60
B) 100 to 150
C) 500 to 600
D) 1400 to 1500
Ans. A
34. Which of the following compounds is widely used for algae control?
A) Sodium sulphate
B) Copper sulphate
C) Sodium chloride
D) Calcium chloride
Ans. B
35. Dissolved oxygen in streams is
A) Maximum at noon
B) Minimum at noon
C) Maximum at midnight
D) Same throughout the day
Ans. A
36. If the coli form bacteria is present in a sample of water, then the coli-form test to be conducted is
(i) Presumptive coli-form test
(ii) Confirmed coli-form test
t(iii) Completed coli-form test
The correct answer is
A) Only (i)
B) Both (i) and (ii)
C) Both (i) and (iii)
D) All (i), (ii) and (iii)
Ans. D
37. As compared to higher pH values, the contact period required for efficient chlorin action at lower pH values is
A) Smaller
B) Larger
C) Same
D) None of the above
Ans. A
38. Standard BOD is measured at
A) 20°C – 1day
B) 25°C – 3day
C) 20°C – 5day
D) 30°C – 5day
Ans. C
39. The velocity of flow of water in a sedimentation tank is about
A) 5 to 10 cm/sec
B) 15 to 30 cm/sec
C) 15 to 30 cm/minute
D) 15 to 30 cm/hour
Ans. C
40. Alum as a coagulant is found to be most effective when pH range of water is
A) 2 to 4
B) 4 to 6
C) 6 to 8
D) 8 to 10
Ans. C
41. The percentage of filtered water, which is used for backwashing in rapid sand filters, is about
A) 0.2 to 0.4
B) 0.4 to 1.0
C) 2 to 4
D) 5 to 7
Ans. C
42. For a country like India, where rain fall is mainly confined to one season, the suitable sewerage system will be
A) Separate system
B) Combined system
C) Partially combined system
D) Partially separate system
Ans. A
43. If the time of concentration is 9 minutes, then the intensity of rain fall according to British Ministry of Health formula will be
A) 4 mm/hr
B) 10 mm/hr
C) 20 mm/hr
D) 40 mm/hr
Ans. D
44. The minimum and maximum diameters of sewers shall preferably be
A) 15 cm and 100 cm
B) 15 cm and 300 cm
C) 30 cm and 450 cm
D) 60 cm and 300 cm
Ans. B
45. Sewage treatment units are designed for
A) Maximum flow only
B) Minimum flow only
C) Average flow only
D) Maximum and minimum flow
Ans. C
46. When there is no recirculation of sewage, then recirculation factor is
A) 0
B) 1
C) In fin ity
D) None of the above
Ans. B
47. The polluted water is one which
A) Contain s pathogenic bacteria
B) Consists of undesirable substances rendering it unfit for drinking and domestic use
C) Is safe and suitable for drinking and domestic use
D) Is contaminated
Ans. B
48. Orthotolidine test is used for determination of
A) Dissolved oxygen
B) Residual chlorin e
C) Biochemical oxygen demand
D) Dose of coagulant
Ans. B
49. The chemical most commonly used to increase speed of sedimentation of sewage is
A) Sulphuric acid
B) Copper sulphate
C) Lime
D) Sodium permanganate
Ans. C
50. The disinfection efficiency of chlorin e increases by
(i) Decreasing the time of contact
(ii) Decreasing the temperature of water
(iii) Increasing the temperature of water
The correct answer is
A) Only (i)
B) Both (i) and (ii)
C) Both (i) and (iii)
D) Only (iii)
Ans. D
51. The layout of distribution system in which water flows towards the outer periphery
A) Rin g system
B) Dead end system
C) Radial system
D) Grid iron system
Ans. C
52. The type of valve which allows water to flow in one direction but prevents its flow in the reverse direction is
A) Reflux valve
B) Sluice valve
C) Air relief valve
D) Pressure relief valve
Ans. A
53. The suitable system of sanitation for area of distributed rain fall throughout the year with less intensity is
A) Separate system
B) Combined system
C) Partially separate system
D) Partially combined system
Ans. B
54. The main disadvantage of cement concrete sewers is
A) Less strength
B) Difficulty in construction
C) Difficulty in transportation due to heavy weight
D) Less life
Ans. C
55. Settling velocity increases with
A) Specific gravity of solid particles
B) Size of particles
C) Depth of tank
D) Temperature of liquid
Ans. C
56. Facultative bacteria are able to work in
A) Presence of oxygen only
B) Absence of oxygen only
C) Presence as well as in absence of oxygen
D) Presence of water
Ans. C
57. The suitable layout of distribution system for a city with roads of rectangular pattern is
A) Grid iron system
B) Dead end system
C) Rin g system
D) Radial system
Ans. A
58. The slope of sewer shall be
A) Given in the direction of natural slope of ground
B) Given in the direction opposite to natural slope of ground
C) Zero
D) Steeper than 1 in 20
Ans. A
59. The correct relation between theoretical oxygen demand (TOD), Biochemical oxygen demand (BOD) and Chemical oxygen demand (COD) is given by
A) TOD > BOD > COD
B) TOD > COD > BOD
C) BOD > COD > TOD
D) COD > BOD > TOD
Ans. B
60. The working conditions in Imhoff tanks are
A) Aerobic only
B) Anaerobic only
C) Aerobic in lower compartment and anaerobic in upper compartment
D) Anaerobic in lower compartment and aerobic in upper compartment
Ans. D
61. The pipe which is used to carry the discharge from sanitary fittings like bath rooms, kitchens etc. is called
A) Waste pipe
B) Soil pipe
C) Vent pipe
D) Anti-siphonage pipe
Ans. A
62. If the total hardness of water is greater than its total alkalinity, the carbonate hardness will be equal to
A) Total alkalinity
B) Total hardness
C) Total hardness total alkalinity
D) Non carbonate hardness
Ans. A
63. For a given discharge, the efficiency of sedimentation tank can be increased by
A) Increasing the depth of tank
B) Decreasing the depth of tank
C) Increasing the surface area of tank
D) Decreasing the surface area of tank
Ans. C
64. Air bin din g phenomena in rapid sand filters occur due to
A) Excessive negative head
B) Mud ball formation
C) Higher turbidity in the effluent
D) Low temperature
Ans. A
65. The suitable method for disinfection of swimming pool water is
A) Ultra violet rays treatment
B) Lime treatment
C) By using potassium permanganate
D) Chlorination
Ans. A
66. The commonly used material for water supply pipes, which has the properties of being strong, not easily corroded and long life but is heavy and brittle, is
A) Steel
B) Cast iron
C) Copper
D) Rein forced cement concrete
Ans. B
67. The water carriage system of collection of waste product
A) Is cheaper in initial cost than dry conservancy system
B) Requires treatment before disposal
C) Creates hygienic problem
D) All of the above
Ans. B
68. The effect of increasing diameter of sewer on the self-cleansing velocity is
A) To decrease it
B) To increase it
C) Fluctuating
D) Nil
Ans. B
69. The rate of BOD exerted at any time is
A) Directly proportional to BOD satisfied
B) Directly proportional to BOD remain in g
C) Inversely proportional to BOD satisfied
D) Inversely proportional to BOD remain in g
Ans. B
70. Generally, the detention period for grit chambers is kept as
A) 1 minute
B) 5 min utes
C) 24 hours
D) 12 hours
Ans. A
71. Sludge volume index is defined as the ratio of
A) Percentage of sludge by volume to percentage of suspended solids by weight
B) Percentage of sludge by volume to percentage of total solids by weight
C) Percentage of suspended solids by weight to percentage of sludge by volume
D) Percentage of total solids by weight to percentage of sludge by volume
Ans. A
72. The biochemical treatment of sewage effluents is essentially a process of
A) Oxidation
B) Dehydration
C) Reduction
D) Alkalinization
Ans. A
73. Which of the following causes a decrease in per capita consumption?
A) Use of metering system
B) Good quality of water
C) Better standard of living of the people
D) Hotter climate
Ans. A
74. The suitable method of the forecasting population for a young and rapidly increasing city is
A) Arithmetical increase method
B) Geometrical increase method
C) Incremental increase method
D) Graphical method
Ans. B
75. Which of the following is not a defined as water borne disease?
A) Dysentery
B) Cholera
C) Typhoid
D) Malaria
Ans. D
76. Standard EDTA (ethylene diamine tetra acetic acid) solution is used to determine the
A) Hardness in water
B) Turbidity in water
C) Dissolved oxygen in water
D) Residual chlorin e in water
Ans. A
77. The settling velocity of a particle in a sedimentation tank depends on
A) Depth of tank
B) Surface area of tank
C) Both depth and surface area of tank
D) None of the above
Ans. B
78. The detention period in the coagulation tanks is usually kept as the
A) 1 to 2 minutes
B) 30 to 45 minutes
C) 2 to 6 hours
D) 2 to 6 days
Ans. C
79. Period of cleaning of slow sand filters is about the
A) 24 – 48 hours
B) 10 – 12 days
C) 2 – 3 months
D) 1 – 2 year
Ans. C
80. The process in which the chlorine action is done beyond the break point is known as the
A) Pre-chlorin action
B) Post chlorin action
C) Super chlorin action
D) Break point chlorin action
Ans. C
81. Disinfection efficiency is the
A) Reduced at higher pH value of water
B) Unaffected by pH value of water
C) Increased at higher pH value of water
D) Highest at pH value equal to 7
Ans. A
82. The suitable layout of a distribution system for the irregularly growing town is as
A) Dead end system
B) Grid iron system
C) Radial system
D) Rin g system
Ans. A
83. A sewer that receives the discharge of a number of house sewers is called as
A) House sewer
B) Lateral sewer
C) In tercepting sewer
D) Sub-main sewer
Ans. B
84. The time of concentration is defined as the
A) The time taken by the rain fall water to run from most distant point of water shed to the inlet of sewer
B) The time required for the flow of water in sewer to the point under consideration
C) Sum of (A) and (B)
D) Difference of (A) and (B)
Ans. C
85. Most suitable section of the sewer in separate sewage system is the
A) Rectangular section
B) Circular section
C) Standard form of egg-shaped sewer
D) Modified egg shaped section
Ans. B
86. The pathogens can be killed by the
A) Nitrification
B) Chlorin action
C) Oxidation
D) None of the above
Ans. B
87. The minimum content of dissolved oxygen which should always be present in the water in order to save the aquatic life is as
A) 1 ppm
B) 4 ppm
C) 10 ppm
D) 40 ppm
Ans. B
88. If the sewage contains grease and fatty oils, these are removed by
A) Grit chambers
B) Detritus tanks
C) Skimming tanks
D) Sedimentation tanks
Ans. C
89. Composting and lagooning are the methods of the
A) Sludge digestion
B) Sludge disposal
C) Sedimentation
D) Filtration
Ans. B
90. The gas from sludge digestion tank is mainly composed of the
A) Nitrogen
B) Carbon dioxide
C) Hydrogen sulphide
D) Methane
Ans. D
91. Assertion A: The consumption of the water increases with increase in the distribution pressure. Reason R: Higher the distribution pressure causes more loss and waste of water Select your answer according to the coding system given below
A) Both A and R is true and R is the correct explanation of A
B) Both A and R is true but R is not the correct explanation of A
C) A is true but R is false
D) A is false but R is true
Ans. A
92. The depression of water table in a well due to the pumping will be maximum (Where R is the radius of in fluence)
A) At a distance R from the well
B) Close to the well
C) At a distance R/2 from the well
D) None of the above
Ans. B
93. Ground water is usually free from the
A) Suspended impurities
B) Dissolved impurities
C) Both suspended and dissolved impurities
D) None of the above
Ans. A
94. On the standard silica scale, the turbidity in drinking water should be limited to the
A) 10 ppm
B) 20 ppm
C) 30 ppm
D) 50 ppm
Ans. A
95. The settling velocity of a particle inside a sedimentation tank increases if
A) Particle size is decreased
B) The surface area of tank is increased
C) The depth of tank is decreased
D) None of the above
Ans. D
96. As compared to the rapid sand filters, to the slow sand filters gives the
(i) Slower filtration rate
(ii) Higher filtration rate
(iii) Lesser efficiency in removal of bacteria
(iv) Higher efficiency in removal of bacteria
The correct answer is
A) (i) and (ii)
B) (ii) and (iii)
C) (i) and (iv)
D) (ii) and (iv)
Ans. C
97. Chlorine demand of water is equal to the
A) Applied chlorin e
B) Residual chlorin e
C) Sum of applied and residual chlorin e
D) Difference of applied and residual chlorin e
Ans. D
98. In case of lime-soda process
A) Only carbonate hardness is removed
B) Only noncarbonated hardness is removed
C) Lime reduces the carbonate hardness and soda-ash removes the non-carbonate hardness
D) Lime reduces the non-carbonate hardness and soda-ash removes the carbonate hardness
Ans. C
99. Which of the following methods of analysis of the water distribution system is most of the suitable for long and narrow type pipe system?
A) Circle method
B) Equivalent pipe method
C) Hardy cross method
D) Electrical analysis method
Ans. B
100. Which of the following sewers is normally preferred for combined system of the sewage?
A) Circular sewer
B) Egg shaped sewer
C) Rectangular sewer
D) None of the above
Ans. B
101. An egg-shaped section of the sewer
A) Is economical than circular section
B) Provides self-cleansing velocity at low discharges
C) Is more stable than circular section
D) Is easy to construct
Ans. B
102. Sewage treatment units are normally designed for the
A) 5 – 10 years
B) 15 – 20 years
C) 30-40 years
D) 40 – 50 years
Ans. B
103. The means of the access for inspection and cleaning of sewer line is known as the
A) In let
B) Manhole
C) Drop manhole
D) Catch basin
Ans. B
104. The maximum efficiency of BOD removal is achieved in the
A) Oxidation pond
B) Oxidation ditch
C) Aerated lagoons
D) Trickling filters
Ans. B
105. In case of the same solid content, if the quantity of sludge with moisture content of 98% is X, then the quantity of the sludge with moisture content of 96% will be as follows
A) X/4
B) X/2
C) X
D) 2X
Ans. B
106. The process of the lagooning is primarily a means of
A) Reducing the excessive flow in sewers
B) Disposing of sludge
C) Increasing the capacity of storage reservoirs
D) Increasing flow of sewage through imhoff tanks
Ans. B
107. The per capital consumption of a locality is affected by the
(i) Climatic conditions
(ii) Quality of water
(iii) Distribution pressure
The correct answer is
A) Only (i)
B) Both (i) and (ii)
C) Both (i) and (iii)
D) All (i), (ii) and (iii)
Ans. D
108. Select the properly correct relationship between porosity (N), specific yield (y) and specific retention (R)
A) N = y + R
B) y = N + R
C) R = N + y
D) R > (N + y)
Ans. A
109. The maximum permissible limit for fluoride in the drinking water is
A) 0.1 mg/litre
B) 1.5 mg/litre
C) 5 mg/litre
D) 10 mg/litre
Ans. B
110. The dissolved oxygen level in the natural unpolluted waters at normal temperature is found to be of the order of
A) 1 mg/litre
B) 10 mg/litre
C) 100 mg/litre
D) 1000 mg/litre
Ans. B
111. The amount of the coagulant needed for the coagulation of water increases with the
(i) Increase in turbidity of water
(ii) Decrease in turbidity of water
(iii) Increase in temperature of water
(iv) Decrease in temperature of water
The correct answer is
A) (i) and (ii)
B) (i) and (iv)
C) (ii) and (iii)
D) (ii) and (iv)
Ans. B
112. The rate of Alteration of pressure filters is basically
A) Less than that of slow sand filters
B) In between the filtration rate of slow sand filters and rapid sand filters
C) Greater than that of rapid sand filters
D) Equal to that of slow sand filters
Ans. C
113. The treatment of water with bleaching powder is known as
A) pre-chlorin action
B) Super chlorin action
C) De-chlorin action
D) Hypo-chlorin action
Ans. D
114. Activated carbon is used for the
A) Disinfection
B) Removing hardness
C) Removing odours
D) Removing corrosiveness
Ans. C
115. A pipe conveying the sewage from plumbing system of a single building to a common sewer or point of immediate disposal is called as
A) House sewer
B) Lateral sewer
C) Main sewer
D) Sub-main sewer
Ans. A
116. The self-cleansing velocity for all type sewers in India is usually
A) Less than 1.0 m/sec
B) 1.0 m/sec to 1.2 m/sec
C) 1.5 m/sec to 2.0 m/sec
D) 3.0 m/sec to 3.5 m/sec
Ans. B
117. The type of the sewer which is suitable for both the combined and separate system is
A) Circular sewer
B) Egg shaped sewer
C) Horseshoe type sewer
D) Semi-elliptical sewer
Ans. B
118. In case of a BOD test, 1.0 ml of raw sewage was diluted to 100 ml and the dissolved oxygen concentration of diluted sample at the beginning was 6 ppm and it was 4 ppm at the end of the 5 day in cubation at 20°C. The BOD of raw sewage will be as
A) 100 ppm
B) 200 ppm
C) 300 ppm
D) 400 ppm
Ans. B
119. Corrosion in case of concrete sewers is caused by the
A) Septic conditions
B) Dissolved oxygen
C) Chlorin e
D) Nitrogen
Ans. A
120. The main disadvantage of the oxidation pond is that
A) Large area is required for construction
B) Maintenance and operation cost are high
C) BOD removal is very low
D) None of the above
Ans. A
121. Most of the bacteria in sewage are the type of
A) Parasitic
B) Saprophytic
C) Pathogenic
D) Anaerobic
Ans. B
122. The hourly variation factor is usually taken as the
A) 1.5
B) 1.8
C) 2
D) 2.7
Ans. A
123. The maximum discharge of a tube well is about the
A) 5 litres/sec
B) 50 litres/sec
C) 500 litres/sec
D) 1000 litres/see
Ans. B
123 A. Turbidity is measured on the
A) Standard silica scale
B) Standard cobalt scale
C) Standard platin um scale
D) Platin um cobalt scale
Ans. A
124. The overflow rate for plain sedimentation tanks is generally about
A) 500 to 750 litres/hour/m2
B) 1000 to 1250 litres/hour/m2
C) 1250 to 1500 litres/hour/m2
D) 1500 to 2000 litres/hour/m2
Ans. A
125. Assertion A: The slow sand filters are more efficient in removal of bacteria than the rapid sand filters. Reason R: The sand used in case of slow sand filters is finer than that in rapid sand filters
A) Both A and R is true and R is the correct explanation of A
B) Both A and R is true but R is not the correct explanation of A
C) A is true but R is false
D) A is false but R is true
Ans. A
126. Which of the following chemical compounds can be easily used for de-chlorin action of
A) Carbon dioxide
B) Bleaching powder
C) Sulphur dioxide
D) Chloramines
Ans. C
127. Hardy cross method of analysis of the distribution system is incase of
(i) Involves successive trials
(ii) Takes economic aspects in to account
(iii) Is time consuming
The correct answer is
A) Only (i)
B) (i) and (ii)
C) (i) and (iii)
D) All are correct
Ans. C
128. The average rate of the water consumption per head per day as per Indian Standard is as follows
A) 100 litres
B) 135 litres
C) 165 litres
D) 200 litres
Ans. B
129. The hydraulic mean depth (HMD) for an egg-shaped sewer line flowing two-third full is
A) Equal to HMD when flowing full
B) Less than HMD when flowing full
C) Greater than HMD when flowing full
D) None of the above
Ans. C
130. Select the correct statement as mentioned below.
A) 5 day BOD is the ultimate BOD
B) 5 day BOD is greater than 4 day BOD keeping other conditions same
C) 5 day BOD is less than 4 day BOD keeping other conditions same
D) BOD does not depend on time
Ans. C
131. Laying of sewers lines is usually done with the help of the
A) A Theodolite
B) A compass
C) Sight rails and boning rods
D) A plane table
Ans. C
132. For normal sludge, the value of sludge index for Indian conditions is as
A) 0 to 50
B) 50 to 150
C) 150 to 350
D) 350 to 500
Ans. C
133. If the average daily consumption of a city is 100,000 m3, then the maximum daily consumption on peak hourly demand will be as follows
A) 100000 m3
B) 150000 m3
C) 180000 m3
D) 270000 m3
Ans. D
134. The most common cause of acidity in the water is due to
A) Carbon dioxide
B) Oxygen
C) Hydrogen
D) Nitrogen
Ans. A
135. The amount of residual chlorine left in the public water supply for safety purpose against the pathogenic bacteria is near about
A) 0.01 to 0.05 ppm
B) 0.05 to 0.5 ppm
C) 0.5 to 1.0 ppm
D) 1.0 to 5.0 ppm
Ans. B
136. The detention period and overflow rate respectively for the case of plain sedimentation as compared to sedimentation with coagulation are generally observed
A) Less and more
B) Less and less
C) More and less
D) More and more
Ans. C
137. The effective size of sand particles used in case of slow sand filters is as follows
A) 0.25 to 0.35 mm
B) 0.35 to 0.60 mm
C) 0.60 to 1.00 mm
D) 1.00 to 1.80 mm
Ans. A
138. In chlorination, with the rise in temperature of the water, death rate of bacteria is
A) Increases
B) Decreases
C) Remain s unaffected
D) None of the above
Ans. A
139. The method of analysis of distribution system in which the domestic supply is neglected and fire demand is considered is
A) Circle method
B) Equivalent pipe method
C) Electrical analysis method
D) Hardy cross method A
Ans. A
140. The specific gravity of sewage is termed as
A) Much greater than 1
B) Slightly less than 1
C) Equal to 1
D) Slightly greater than 1
Ans. D
141. Which of the following of retards the self-purification of stream?
A) Higher temperature
B) Sunlight
C) Satisfying oxygen demand
D) None of the above
Ans. D
142. Sewerage system is designed for the
A) Maximum flow only
B) Minimum flow only
C) Average flow only
D) Maximum and minimum flow
Ans. D
143. In case of facultative stabilization pond, the sewage is treated by the
A) Aerobic bacteria only
B) Algae only
C) Dual action of aerobic bacteria and anaerobic bacteria
D) Sedimentation
Ans. C
144. A pipe which is installed inside the house drainage to preserve the water seal of traps is called as
A) Vent pipe
B) Anti-siphonage pipe
C) Waste pipe
D) Soil pipe
Ans. B
145. The distribution mains are designed for the
A) Maximum daily demand
B) Maximum hourly demand
C) Average daily demand
D) Maximum hourly demand on maximum day
Ans. D
146. The type of valve, which is provided on the suction pipe in a tube-well, is basically the
A) Air relief valve
B) Reflux valve
C) Pressure relief valve
D) Sluice valve
Ans. B
147. Alkalinity in the water is expressed as milligrams per litre in terms of equivalent of the
A) Calcium carbonate
B) Magnesium carbonate
C) Sodium carbonate
D) Calcium hydroxide
Ans. A
