environmental engineering Mcqs
51. The main disadvantage of cement concrete sewers is________________?
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A. difficulty in transportation due to heavy weight

B. difficulty in construction

C. less strength

D. less life

52. Orthotolidine test is used for determination of________________?
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A. residual chlorine

B. dissolved oxygen

C. biochemical oxygen demand

D. dose of coagulant

53. The process of lagooning is primarily a means of________________?
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A. increasing the capacity of storage re-servoirs

B. reducing the excessive flow in sewers

C. increasing flow of sewage through imhoff tanks

D. disposing of sludge
54. Sewage treatment units are designed for_______________?
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A. average flow only

B. maximum and minimum flow

C. maximum flow only

D. minimum flow only

55. The type of valve, which is provided on the suction pipe in a tube-well, is____________?
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A. air relief valve

B. pressure relief valve

C. reflux valve

D. sluice valve

56. The correct relation between theoretical oxygen demand (TOD), Biochemical oxygen demand (BOD) and Chemical oxygen demand (COD) is given by_______________?
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A. TOD>COD>BOD

B. TOD>BOD>COD

C. COD>BOD>TOD

D. BOD>COD>TOD

57. Double filtration is used_______________?
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A. to increase the filtration slow sand filters capacity of

B. for isolated buildings like pools, hotels etc swimming

C. all of the above

D. to increase the filtration rapid sand filters capacity of

58. The overflow rate for plain sedimentation tanks is about__________________?
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A. 500 to 750 litres/hour/ m2

B. 1500 to 2000 litres/hour/m2

C. 1000 to 1250 litres/hour/ m2

D. 1250 to 1500 litres/hour/m2

59. The chemical most commonly used to increase speed of sedimentation of sewage is_______________?
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A. sodium permanganate

B. copper sulphate

C. sulphuric acid

D. lime
60. Composting and lagooning are the methods of_______________?
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A. sedimentation

B. sludge disposal

C. sludge digestion

D. filtration

61. The characteristics of fresh and septic sewage respectively are____________________?
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A. acidic and alkaline

B. alkaline and acidic

C. both acidic

D. both alkaline

62. Standard BOD is measured at________________?
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A. 20C 5day

B. 25C- 3day

C. 20C 1day

D. 30C- 5day

63. The time of concentration is defined as_______________?
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A. sum of (A) and (B)

B. the time taken by rainfall water to run from most distant point of water shed to the inlet of sewer

C. the time required for flow of water in sewer to the point under consideration

D. difference of (A) and (B)

64. Sewerage system is usually designed for_________________?
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A. 10 years

B. 25 years

C. 75 years

D. 50 years

65. Activated carbon is used for_____________?
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A. removing odours

B. removing corrosiveness

C. removing hardness

D. disinfection

66. The specific gravity of sewage is_______________?
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A. slightly less than 1

B. much greater than 1

C. equal to 1

D. slightly greater than 1
67. In facultative stabilization pond, the sewage is treated by________________?
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A. aerobic bacteria only

B. sedimentation

C. algae only

D. dual action of aerobic bacteria and anaerobic bacteria
68. The effective size of sand particles used in slow sand filters is_______________?
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A. 0.35 to 0.60 mm

B. 1.00 to 1.80 mm

C. 0.25 to 0.35 mm

D. 0.60 to 1.00 mm

69. The percentage of filtered water, which is used for backwashing in rapid sand filters, is about______________?
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A. 5 to 7

B. 0.2 to 0.4

C. 2 to 4

D. 0.4 to 1.0

70. If the time of concentration is 9 minutes, then the intensity of rainfall according to British Ministry of Health formula will be__________________?
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A. lOmm/hr

B. 20 mm/hr

C. 40 mm/hr

D. 4 mm/hr

71. The suitable layout of a distribution system for irregularly growing town is_______________?
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A. grid iron system

B. ring system

C. radial system

D. dead end system
72. The per capital consumption of a locality is affected by_________________?
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A. quality of water

B. climatic conditions

C. distribution pressure</strong>

D. correct answer is?

73. In lime-soda process________________?
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A. only carbonate hardness is removed

B. lime reduces the non-carbonate hard-ness and soda-ash removes the carbonate hardness

C. lime reduces the carbonate hardness and soda-ash removes the non-carbonate hardness

D. only non-carbonate hardness is re-moved

74. The maximum permissible limit for flouride in drinking water is______________?
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A. 5 mg/litre

B. 1.5 mg/litre

C. 0.1 mg/litre

D. 10 mg/litre

75. The amount of residual chlorine left in public water supply for safety against pathogenic bacteria is about______________?
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A. 1.0 to 5.0 ppm

B. 0.5 to 1.0 ppm

C. 0.01 to 0.05 ppm

D. 0.05 to 0.5 ppm
76. The devices which are installed for drawing water from the sources are called______________?
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A. aquifers

B. aquiclude

C. filters

D. intakes
77. Which of the following methods of analysis of water distribution system is most suitable for long and narrow pipe system ?
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A. circle method

B. Hardy cross method

C. equivalent pipe method

D. electrical analysis method

78. As compared to geometrical increase method of forecasting population, arithmetical increase method gives________________?
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A. accurate value

B. lesser value

C. higher value

D. same value

79. The alum, when added as a coagulant in water_______________?
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A. decreases pH value of water

B. does not affect pH value of water

C. increases pH value of water

D. does not require alkalinity in water for flocculation

80. The water carriage system of collection of waste product________________?
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A. is cheaper in initial cost than dry conservancy system

B. requires treatment before disposal

C. all of the above

D. creates hygenic problem

81. Turbidity is measured on_______________?
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A. standard cobalt scale

B. standard platinum scale

C. standard silica scale

D. platinum cobalt scale

82. The process in which the chlorination is done beyond the break point is known as_________________?
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A. break point chlorination

B. super chlorination

C. prechlorination

D. post chlorination

83. The main disadvantage of oxidation pond is that________________?
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A. BOD removal is very low

B. maintenance and operation cost are high

C. large area is required for construction

D. none of the above

84. As compared to shallow-wells, deep wells have______________?
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A. more depth

B. less depth

C. less discharge

D. more discharge
85. Laying of sewers is usually done with the help of________________?
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A. a theodolite

B. sight rails and boning rods

C. a plane table

D. a compass

86. Which of the following causes a decrease in per capita consumption ?
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A. use of metering system

B. good quality of water

C. hotter climate

D. better standard of living of the people

87. The treatment of water with bleaching powder is known as________________?
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A. hypochlorination

B. super chlorination

C. dechlorination

D. prechlorination

88. Settling velocity increases with_______________?
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A. temperature of liquid

B. specific gravity of solid particles

C. depth of tank

D. size of particles

89. The hourly variation factor is usually taken as______________?
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A. 1.8

B. 2.7

C. 2

D. 1.5
90. The maximum efficiency of BOD removal is achieved in______________?
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A. oxidation ditch

B. aerated lagoons

C. oxidation pond

D. trickling filters

91. The most commonly used sewer under culverts is_______________?
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A. circular brick sewer

B. circular cast iron sewer

C. semi-elliptical sewer

D. horse-shoe type sewer

92. As compared to cast iron pipes, steel pipes are______________?
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A. costlier

B. heavier

C. less susceptible to corrosion

D. stronger
93. On standard silica scale, the turbidity in drinking water should be limited to_______________?
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A. 30 ppm

B. 20 ppm

C. 50 ppm

D. 10 ppm
94. The distribution mains are designed for________________?
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A. maximum daily demand

B. average daily demand

C. maximum hourly demand

D. maximum hourly demand on maximum day
95. Septic tank is a______________?
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A. aeration tank</strong>

B. settling tank

C. correct answer is?

D. digestion tank

96. Hardy cross method of analysis of distribution system________________?
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A. involves successive trials

B. takes economic aspects into account

C. is time consuming</strong>

D. correct answer is?

97. Select the correct relationship between porosity (N), specific yield (y) and specific retention (R)________________?
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A. R > (N + y)

B. R = N + y

C. y = N + R

D. N = y + R
98. Which of the following unit works in anaerobic conditions ?
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A. activated sludge treatment

B. trickling filters

C. sedimentation tank

D. sludge digestion tank
99. In chlorination, with the rise in temperature of water, death rate of bacteria____________?
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A. none of the above

B. remains unaffected

C. decreases

D. increases
100. The slope of sewer shall be__________________?
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A. zero

B. given in the direction of natural slope of ground

C. given in the direction opposite to natural slope of ground

D. steeper than 1 in 20