IMPORTANT OBJECTIVE QUESTIONS ON ENVIRONMENT ENGINEERING

Pankaj Sharma

Royal Member
Staff member
Important Objective Questions On Environment Engg.

1. Turbidity of raw water is a measure of
(A) Suspended solids
(B) Acidity of water
(C) B.O.D.
(D) None of these


2. If the chosen diameter of a pipe, is less than the economical diameter
(A) Cost of pipe will be less
(B) Head loss will be high
(C) Cost of pumping will be more than saving

(D) All the above

3. The process of passing water through beds of granular materials, is called
(A) Screening
(B) Sedimentation
(C) Filtration
(D) None of these


4. For the prediction of future population of a city, the factor to be considered, is
(A) Births
(B) Deaths
(C) Migrants
(D) All the above


5. Mathamoglobinemia or blue baby disease is caused due to
(A) Chlorides
(B) Nitrites
(C) Nitrates
(D) Sulphides


6. To control the growth of algae in reservoirs, the compound which is used, is
(A) Bleaching powder
(B) Copper sulphate
(C) Lime solution
(D) Alum solution


7. The population of a city in 2000 is 50,000. The average increase in population over last 8 decades is
7500 and average incremental increase during 8 decades is 750. The population of the city based
on incremental method, in the year 2020 will be
(A) 55,000
(B) 60,500
(C) 66,500
(D) 72,500


8. The bacterias which require free oxygen for their survival, are called
(A) Aerobic bacterias
(B) Anaerobic bacterias
(C) Facultative bacteria
(D) None of these


9. The main disadvantage of hard water, is
(A) Greater soap consumption
(B) Scaling of boilers
(C) Corrosion and incrustation of pipes
(D) All the above


10. The bed slope in slow sand filters, is generally kept
(A) 1 in 50
(B) 1 in 75
(C) 1 in 100
(D) 1 : 200


11. Pick up the incorrect statement from the following:
(A) The pH value of water indicates the logarithm of reciprocal of hydrogen ion concentration in
water
(B) Higher value of pH means lower hydrogenion concentration
(C) Lower value of pH means higher hydrogen ion contraction
(D) Lower value of pH gives alkaline solution


12. Mostly used coagulant, is
(A) Chlorine
(B) Alum
(C) Lime
(D) Bleaching powder


13.Normal values of overflow rate for plain sedimentation tank, is
(A) 250 to 500 litres/hr/m2

(B) 500 to 750 litres/hr/m2
(C) 750 to 1000 litres/hr/m 2
(D) 1000 to 1250 litres/hr/m 2


14. The maximum permissible hardness for public supplies is
(A) 95 mg/litre
(B) 105 mg/litre
(C) 115 mg/litre
(D) 125 mg/litre


15. The chlorine supply cylinders are generally kept at 38°C to 40°C to prevent
(A) Conversion into crystals
(B) It from burning
(C) It from explosion
(D) None of these


16. Property of earth to allow water to pass through it, is known as
(A) Perviousness
(B) Porosity
(C) Permeability
(D) Transmissibility


17. Plain chlorination is used for water
(A) Obtained from clear lakes
(B) Consumed during emergencies
(C) Supplies to armies during war

(D) All the above


18. A city supply includes
(A) Domestic water demand
(B) Industrial and commercial water demands
(C) Demand for public uses and fire

(D) All the above


19. If L, B and D length, breadth and depth of water in a rectangular sedimentation tank of total
discharge Q, the settling velocity, is
(A) Q/H
(B) Q/D
(C) Q/(D × B)

(D) Q/(L × B)


20. Rapid gravity filters
(A) Were developed by G.W. Fuller
(B) Make use of coarser sand with effective size as 0.5 mm
(C) Yield as high as 30 times the yield of slow sand filters

(D) All the above


21. Maximum threshold number permitted for indicating the odour of public water supplies, is
(A) 1
(B) 2

(C) 3
(D) 4


22. In a rapid sand filter, air binding is caused due to excessive
(A) Negative pressure
(B) Pressure
(C) Turbidity
(D) Water pressure


23. To remove very fine suspended particles from water, the method adopted is
(A) Screening
(B) Sedimentation
(C) Boiling
(D) Filtration


24. 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


25. The average domestic consumption under normal conditions in an Indian city per day per person,
is

(A) 105 litres
(B) 115 litres
(C) 125 litres
(D) 135 litres


26. Permanent hardness of water can be removed by
(A) Adding alum
(B) Adding lime
(C) Adding chlorine
(D) Zeolite process


27. After cleaning a slow sand filter, the filtered water is not used for
(A) 6 hours to 12 hours
(B) 12 hours to 18 hours
(C) 18 hours to 24 hours

(D) 24 hours to 36 hours


28. Velocity of flow of water in plain sedimentation water tank, is normally kept
(A) 3 cm/minute
(B) 10 cm/minute
(C) 20 cm/minute

(D) 30 cm/minute


29. Hard water contains
(A) Calcium
(B) Magnesium bicarbonates
(C) Magnesium sulphate

(D) All the above


30. In a well planned city, the layout of distribution pipes generally adopted, is
(A) Grid-iron system
(B) Interlaced system
(C) Reticulation system

(D) all the above


31. The bacterias which may survive with or without free oxygen, are called
(A) Aerobic bacterias
(B) Anaerobic bacterias

(C) Facultative bacterias
(D) None of these


32. Quality of water is said to be good if it is
(A) Free from suspended matter
(B) Colourless
(C) Free from pathogenic organism

(D) All the above


33. Biochemical Oxygen Demand (B.O.D.) of safe drinking water must be
(A) Nil
(B) 5
(C) 10
(D) 15


34. The ratio of the maximum daily consumption to the average daily demand, is
(A) 1.0
(B) 1.2
(C) 1.4
(D) 1.8


35. The maximum permissible colour for domestic supplies based on cobalt scale, is
(A) 5 ppm
(B) 10 ppm
(C) 15 ppm

(D) 20 ppm


36. Increase in population of a rapidly growing city, may be estimated by
(A) Arithmetical mean method

(B) Geometrical method
(C) Incremental increase method
(D) Graphical comparison method


37. The period of cleaning of a slow sand filter, is usually
(A) 5 to 10 days
(B) Two weeks to three weeks

(C) One month to three months
(D) Three months to six months
38. Efficiency of removing bacterias from raw water by a slow sand filter, is
(A) 80% to 81%
(B) 85% to 86%
(C) 90% to 97%

(D) 98% to 99%


39. The chloride content of treated water for public supplies should not exceed
(A) 100 ppm
(B) 150 ppm
(C) 200 ppm

(D) 250 ppm


40. The percentage of chlorine in fresh bleaching powder is roughly
(A) 50 to 60
(B) 30 to 35
(C) 40 to 50
(D) 20 to 25


41. The multiplying factor, as applied to obtain peak hourly demand in relation to the avg. daily
demand, (per hour of course) is

(A) 1.5
(B) 1.8
(C) 2.0

(D) 2.7


42. The population figure in a growing town are as follows
Year 1970 1980 1990 2000
Population 40000 46000 53000 58000

The predicted population in 2010 by arithmetic regression method is
(A) 62000
(B) 63000
(C) 64000
(D) 65000


43. If the population of a city is 1lakh, avg water consumption is 250lpcd, the fire demand is 61MLD
then the capacity of distribution system should be
(A) 50 MLD
(B) 67.5 MLD
(C) 106 MLD

(D) None


44. Sedimentation may not be required for water from
(A) Shallow well
(B) Deep well
(C) River
(D) Canal


45. For a water sample the total hardness is 200mg/l as CaCO3 and alkalinity is 250mg/l as CaCO3 Then
the carbonate hardness is

(A) 200
(B) 250
(C) 450
(D) 50


46. In the above question Non Carbonate Hardness is
(A) 50
(B) 200
(C) 25

(D) Zero


47. What is the equivalent CaCO3 concentration of 110mg/l of CaCl2
(A) 50mg/l
(B) 58.5 mg/l
(C) 100 mg/l
(D) 117 mg/l


48. The amount of bleaching powder containing 20% available chlorine needed to chlorinate a rural
water supply covering a population of 10000 at 50 lpcd @ 2ppm is
(A) 1 kg*
(B) 5 kg
(C) 0.2 kg
(D) 20 kg


49. Valve which allows water in one direction only is known as
(A) Sluice valve
(B) Scour valve
(C) Air valve

(D) Reflux valve


50. Rate of filteration of slow sand filter in L/hr/m2 is
(A) 100 to 200
(B) 3000 to 6000
(C) 6000 to 15000
(D) 15000 to 18000


51. 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


52. For the open drain (N = 0.025) shown in the below figure, the discharge is
(A) 26.88 cumecs
(B) 27.88 cumecs

(C) 28.88 cumecs
(D) 29.88 cumecs


53. 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


54. 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


55. 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


56. 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)


57. 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


58. Imhoff cone is used to measure
(A) Total organic solids
(B) Total solids
(C) Total inorganic solids

(D) Settelable solids


59. Dilution method of disposing of 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


60. 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

61. In a sedimentation tank (length L, width B, depth D) the settling velocity of a particle for a
discharge Q, is

(A) Q/(B × D)
(B) Q/(L × D)
(C) Q/L

(D) Q/(B × L)


62. 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


63. 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


64. 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


65. The average temperature of sewage in India, is
(A) 10°C
(B) 15°C

(C) 20°C
(D) 25°C


66. 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


67. If 2% solution of a sewage sample is incubated for 5 days at 20°C and depletion of oxygen was
found to be 5 ppm, B.O.D. of the sewage is

(A) 200 ppm
(B) 225 ppm
(C) 250 ppm
(D) None of these


68. 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


69. The pH value of fresh sewage is usually
(A) Equal to 7

(B) More than 7
(C) Less than 7
(D) Equal to zero B


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

(A) Lung cancer
(B) Skin cancer
(C) Bronchitis
(D) Heart disorder


71. The minimum diameter of a sewer is kept
(A) 10 cm
(B) 15 cm
(C) 20 cm
(D) 25 cm


72. 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


73. A manhole is generally provided at each
(A) Bend
(B) Junction
(C) Change of gradient

(D) All the above


74. Facultative bacteria survive in
(A) The presence of oxygen
(B) The absence of oxygen

(C) Both cases (a) and (b)
(D) Neither (a) nor (b)


75. 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


76. 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


77. 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


78. Before discharging the foul sewage into rivers, it is generally treated by
(A) Screening
(B) Sedimentation
(C) Oxidation
(D) All the above


79. To test chemical oxygen demand (C.O.D.) of sewage, organic matter is oxidised by potassium
dichromate in the presence of
(A) Hydrochloric acid
(B) Sulphuric acid
(C) Nitric acid
(D) Citric acid


80. The gas evolved in sewers is
(A) Carbondioxide
(B) Hydrogen sulphide
(C) Methane
(D) All of these


81. The slope of a 1.0m diameter concrete sewer laid at a slope of 1 in 1000, develops a velocity of
1m/s when flowing full. The velocity of flow the sewer have when it is flowing half full will be

(A) 0.5 m/s
(B) √1m/s
(C) 1m/s
(D) 2.0 m/s


82. To remove floating matter like papers, rags etc. the unit used is
(A) screens
(B) grit chambers
(C) imhoff tank
(D) septic tank


83. The secondary treatment of sewage is carried out by the use of
(A) screens
(B) Grit chamber
(C) Trickling Filter
(D) Chlorinators


84. The rate of sludge accumulation in a septic tank is generally of the order of
(A) 10 lt/person/year
(B) 20 lt/person/day
(C) 30 lt/person/year
(D) 100 lt/person/year


85. Anaerobic bacteria play the main role in
(A) Trickling Filter
(B) Activated Sludge Process
(C) Septic Tank
(D) Sedimentation Tank

86. The global warming is caused mainly by
(A) NOx
(B) SOx

(C) CO2
(D) O2


87. The main gas liberated from an anaerobic sludge digestor is
(A) NH3
(B) CH4
(C) CO
(D) CO2


88. The std. 5 day BOD at 20*c , when compared to ultimate BOD is
(A) 60%
(B) 68%
(C) 80%
(D) 90%


89. The permissible limit of arsenic in drinking water as per the guidelines of WHO is
(A) 0.01 PPM
(B) 0.05 PPM
(C) 1 PPM
(D) .005 PPM


90. The population of town as per census records were 200000, 210000,& 230000 for the years 1981
1991, & 2001 respectively.The population of the town as per geometric mean method in the yr
2011 is
(A) 244872
(B) 245872
(C) 246820
(D) None of these


91. The ratio of 5 day BOD to ultimate BOD is about
(A) 1/3
(B) 2/3
(C) 3/4
(D) 1


92. The most suitable solid waste disposal method for rural areas is
(A) land filling
(B) deep well injection
(C) composting
(D) incineration


93. The means of access for inspection and cleaning of sewer line is known as
(A) inlet

(B) manhole
(C) drop manhole
(D) catchbasin


94. Traps are used in household drainage system to
(A) prevent entry of foul gases in the house
(B) restrict the flow of water
(C) provide a particle vaccum
(D) trap the solid waste


95. A trap which admits waste water from floors of bath and kitchen is called
(A) intercepting trap
(B) nahani trap
(C) gulley trap
(D) s trap


96. The minimum dia of an opening of manhole should be
(A) 25cm
(B) 50cm
(C) 75cm
(D) 100cm


97. The ratio of discharge and plan area of a continuous flow type settling tank is known as
(A) surface loading
(B) over flow
(C) over flow rate
(D) all the above


98. The pipe which is used to carry the discharge from sanitary fittings like bathrooms, kitchen etc . is
called
(A) waste pipe
(B) soil pipe
(C) vent pipe
(D) None of these


99. Sewage treatment units are normally designed for
(A) 5-10 yrs
(B) 15-20 yrs
(C) 30-40 yrs
(D) 40-50 yrs


100. In a grit chamber in a sewage treatment plant
(A) flow velocity 0.15-0.30 m/s is kept
(B) depth 0.9-1.2 m is kept
(C) det. Time 1 min
(D) all of these




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