300 Multiple Choice Questions on Water &

Wastewater Pollution, Treatment and Management

1 Sources and Characteristics of Water, Waste Water, Sewage,

Industrial Effluents
1. The State Pollution Control Board gets the power to obtain information to
perform its functions under
o f theW ater(P reventionandControlof P ollution)Act,1974.a)Section21 b)Section33 c)Section30

2. Which of the following statements about the effects of noise pollution are cor-
rect? A. Noise pollution can lead to hearing loss over time. B. It can disturb
wildlife and change animal behaviors. C. It contributes to global warming. D.
Noise pollution can increase stress and anxiety levels.
a) Only B and C b) Only A, C, and D c) Only A, B, and D d) Only A, B, C, and
D
Answer: c) Only A, B, and D
3. Which of the following sources are most likely to have low Dissolved Oxygen
(DO) levels? A. Stagnant pond B. Rapidly flowing river C. Deep underground
well D. Eutrophic lake E. Treated tap water
a) A, D, and E Only b) B, C, and E Only c) A, B, and D Only d) A, C, and D
Only
Answer: d) A, C, and D Only
4. Groundwater is specially prone to excessive hardness due to.
a) Calcium and Sodium ions b) Calcium and Magnesium ions c) Sodium and
Magnesium ions d) Potassium and Calcium ions
Answer: b) Calcium and Magnesium ions
5. When a water body becomes extremely low in nutrient content, then it is called
as
a) Dystrophic b) Oligotrophic c) Mesotrophic d) Eutrophic
Answer: b) Oligotrophic
6. If BOD5 of sewage coming from an industry is 200 kg/day, then its population
equivalent will be
a) 200 b) 2500 c) 3750 d) 1000 e) 5000
Answer: b) 2500
7. Determine ultimate BOD for sewage having 5-day BOD at 20°C as 180 ppm. As-
sume the de-oxygenation constant as 0.8 per day.
a) L0 = 195 mg/l b) L0 = 180 ppm c) L0 = 220 ppm d) L0 = 200 mg/l e) L0
= 150 ppm
Answer: b) L0 = 180 ppm
8. What is the BOD value of strong sewage?
a) 250-350 ppm b) 450-550 ppm c) 550-650 ppm d) 650-750 ppm
Answer: b) 450-550 ppm
9. The amount of oxygen consumed by the aerobic bacteria, which causes the aer-
obic biological decomposition of sewage, is known as

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 a) Biochemical Oxygen Demand (BOD) b) Dissolved Oxygen (DO) c) Chemical
Oxygen Demand (COD) d) None of the above
Answer: b) Dissolved Oxygen (DO)
10. Which of the following statements is/are correct regarding biochemical oxygen
demand (BOD) of sewage?
1. The BOD of water during 5 days at 27°C is generally taken as the standard
demand and is about 882. A 10-day BOD is about 903. The ultimate first state
BOD (Yu) of a given sewage is a fixed quantity and does not depend upon the
temperature.
a) Statement 1 is incorrect, while statements 2 and 3 are correct. b) Statement
1 is correct, while statements 2 and 3 are incorrect. c) Statements 1 and 2 are
correct, while statement 3 is incorrect. d) Statements 1 and 3 are correct, while
statement 2 is incorrect.
Answer: a) Statement 1 is incorrect, while statements 2 and 3 are correct.
11. Turbidity in water is caused by which of these following?
a) Total dissolved solids b) Suspended solids c) Ions d) Heavy metals
Answer: b) Suspended solids
12. What is the relationship between turbidity and TSS for a settled secondary efflu-
ent?
a) TSS = (2.3) x Turbidity b) TSS = (2.0) x Turbidity c) TSS = (2.5) x Turbidity
d) TSS = (1.3) x Turbidity
Answer: a) TSS = (2.3) x Turbidity
13. Which characteristic of water does Calcium contribute to?
a) Hardness b) Suspended solids c) pH d) Colour
Answer: a) Hardness
14. Sodium ions contribute to which characteristic of the water?
a) pH b) Total Dissolved Solids c) Colour d) Suspended solids
Answer: b) Total Dissolved Solids
15. What is the role of chlorine in water treatment?
a) To remove hardness b) To remove ions c) Coagulant agent d) To remove
bacteria
Answer: d) To remove bacteria
16. Which heavy metal is found in cooling water treatment?
a) Zinc b) Arsenic c) Lead d) Copper
Answer: a) Zinc
17. How is hardness represented?
a) Hardness = 2 (Ca2+) +2(Mg2+) b) Hardness = Ca2+ + 2(Mg2+) c) Hardness
= 3(Ca2+) + Mg2+ d) Hardness = 3(Ca2+) +2(Mg2+)
Answer: a) Hardness = 2 (Ca2+) +2(Mg2+)
18. What is the level of Calcium carbonate for a moderately hard water?
a) Hardness >150 ppm b) Hardness= 50 ppm c) Hardness is in between 50-
100 ppm d) Hardness <50 ppm
Answer: c) Hardness is in between 50-100 ppm

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19. How is TDS and conductivity related?
a) TDS = 0.5 conductivity b) Conductivity= 0.5 TDS c) TDS=3 Conductivity d)
TDS=Conductivity
Answer: a) TDS = 0.5 conductivity
20. Colour is contributed to which of the following?
a) Natural organic matter b) Inorganic compounds c) Total dissolved solids
d) Suspended solids
Answer: a) Natural organic matter
21. What will be the Total Organic Carbon (TOC) of coloured water?
a) 100-200ppm b) 100ppm c) 200ppm d) 200-300 ppm
Answer: a) 100-200ppm
22. Which one of the following statements is correct?
a) pKa and pH are positively correlated b) pKa and pH are negatively corre-
lated c) pKa and pH are not correlated d) pKb and pH are positively corre-
lated
Answer: a) pKa and pH are positively correlated
23. Acidity of water is its quantitative capacity to react with a
t oadesignatedpH.a)W eakBase b)StrongAcid c)W eakAc

24. Which indicator is used to estimate the Ca-Hardness of a water sample?

a) Methyl Orange and Phenolphthalein b) Murexide c) Eriochrome Black T
d) Both B and C
Answer: b) Murexide
25. Which method is commonly used to measure turbidity in water samples?
a) Spectrophotometry b) Gravimetric analysis c) Nephelometry d) Titra-
tion
Answer: c) Nephelometry
26. Which of the following is NOT a standard parameter to assess the drinking water
quality?
a) Total coliforms b) coli c) Turbidity d) Methane concentration
Answer: d) Methane concentration
27. Which of the following is a common method for measuring pH in water?
a) Gravimetry b) Conductivity c) Potentiometry d) Turbidity
Answer: c) Potentiometry
28. Which of the following methods is used to determine the alkalinity of water?
a) Titration b) Gravimetry c) Chromatography d) Spectrophotometry
Answer: a) Titration
29. Which of the following is a common method for measuring fluoride concentra-
tion in water?
a) Ion-selective electrode b) Gravimetry c) Turbidity measurement d) Con-
ductivity measurement
Answer: a) Ion-selective electrode
30. Which of the following is a common method for measuring total nitrogen in wa-
ter?

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 a) Kjeldahl digestion b) Ion-exchange chromatography c) Filtration d) Con-
ductivity measurement
Answer: a) Kjeldahl digestion
31. Which method is commonly used to measure TDS in water?
a) Colorimetry b) Conductivity measurement c) Titration d) Spectropho-
tometry
Answer: b) Conductivity measurement
32. Which analytical technique is commonly used to detect and quantify heavy met-
als in water samples?
a) Chromatography b) Atomic Absorption Spectrometry c) Infrared Spec-
troscopy d) Electrochemical analysis
Answer: b) Atomic Absorption Spectrometry
33. Which analytical technique is commonly used to detect and quantify sodium and
potassium in water samples?
a) Chromatography b) Infrared Spectroscopy c) Flame Photometry d) Elec-
trochemical analysis
Answer: c) Flame Photometry
34. Which of the following is a primary standard for pH calibration in water analy-
sis?
a) Sodium chloride b) Potassium hydrogen phthalate c) Sodium bicarbonate
d) Sodium hydroxide
Answer: b) Potassium hydrogen phthalate
35. What is the primary purpose of a gas chromatograph in water analysis?
a) Measure pH levels b) Determine turbidity c) Analyze volatile organic com-
pounds d) Assess electrical conductivity
Answer: c) Analyze volatile organic compounds
36. To analyse metal ions present in the water sample, the sample is recommended
to be collected in separate bottles and
i ttominimizeprecipitation.a)N eutralize b)Acidif y c)Alkalif y d)CooledAnswer:b)Acid

37. Which water parameter needs to be analysed in situ only?

a) pH b) Temperature c) Turbidity d) Conductivity
Answer: b) Temperature
38. Which of the following processes/unit operations of conventional wastewater
treatment is the correct order starting from the inflow?
a) Coagulation Flocculation – Sedimentation – Filtration – Disinfection b) Sed-
imentation – Coagulation Flocculation – Filtration – Disinfection c) Prelimi-
nary treatment, Primary clarifier – Aeration – Secondary clarifier – Filtration –
Disinfection d) Preliminary treatment, Aeration – Primary clarifier – Activated
sludge process – Secondary clarifier – Filtration – Disinfection
Answer: a) Coagulation Flocculation – Sedimentation – Filtration – Disinfection
39. Choose the correct order with an increasing dose of coagulants
I – Restabilization or charge reversal II – No destabilization III – No destabiliza-
tion by sweep floc IV – Destabilization by charge neutralization

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 a) I, II, III, IV b) IV, II, I, III c) II, IV, I, III d) III, I, IV, II
Answer: c) II, IV, I, III
40. The magnitude of the buoyant force acting on a particle in water depends on
which factors?
a) Weight and shape of the particle b) The density of the water and mass of the
particle c) The density of the water and volume of the particle d) The density,
weight, and shape of the particle
Answer: c) The density of the water and volume of the particle
41. What is the key mechanism by which inter-particle contact occurs in a simple
coagulation and flocculation process?
a) Brownian motion, stirring and precipitation b) Thermal motion, Centrifugal
and Gravitational affect c) Gravitational, solvation and drag force d) Ther-
mal motion, bulk fluid motion and particle settling
Answer: d) Thermal motion, bulk fluid motion and particle settling
42. Inactivation of microorganisms/pathogens in water in water distribution sys-
tems is classified as:
a) Primary disinfection b) Secondary disinfection c) Tertiary disinfection
d) Quaternary disinfection
Answer: b) Secondary disinfection
43. At which zone of coagulation and flocculation turbidity is efficiently removed?
a) Restabilization or charge reversal b) No destabilization c) Destabilization
by charge neutralization d) Destabilization by sweep floc
Answer: c) Destabilization by charge neutralization
44. Various species are formed in coagulation and flocculation with alum due to hy-
drolysis of alum salt such as Al 3+, Al(OH) 2 +, Al(OH) 2 +, Al(OH) 3(s), Al(OH) 4 –,
Al(OH) 5 -2. Which species is predominant at pH above 8?
a) Al 3 + b) Al(OH) 2 + c) Al(OH) 3(s) d) Al(OH) 4 –
Answer: d) Al(OH) 4 –
45. Which of the following is not a limitation of natural coagulants such as crude
Moringa oleifera (drumstick) seed extract?
a) It increases colloidal particles b) It increases organic matter and chlorine
demand c) It causes colour, taste odour problems by long periods of water
storage d) Unable to coagulate orthophosphate nitrates
Answer: b) It increases organic matter and chlorine demand
46. Flotation is a physical process used in water treatment to remove
a) Particles that are denser than water b) Pertinacious material from the water
c) Colloidal particles including clay and bacteria d) Particles that are lighter
than water
Answer: d) Particles that are lighter than water
47. Which species is more potent in the disinfection process?
a) HOCl b) OCl – c) Cl2 (g) d) Cl2 (aq)
Answer: a) HOCl
48. Perikinetic flocculation is controlled by:

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 a) Brownian motion b) Both Brownian motion and Intrinsic properties of the
system c) Intrinsic Properties of the system d) Mechanical mixing
Answer: b) Both Brownian motion and Intrinsic properties of the system
49. The majority of the suspended impurities get removed in a slow sand filter through
the process of
a) Mechanical straining b) Sedimentation c) Filtration d) Biological growth
Answer: d) Biological growth
50. Oxygen sag curves occur when
. a)waterlevelsarehigh b)bacteriabreakdownbiodegradablewastes c)whenwaterf lowsquickly d)wh

51. What happens when algae growth deoxygenates the water?

a) Increase in the population of aquatic animals b) Animal mortality c) Bio-
magnification d) Increase in aquatic plants
Answer: b) Animal mortality
52. Eutrophication is less likely to occur in the area
a) That are surrounded by fertilised lands b) Algal bloom is already present.
c) There are numerous aquatic animals d) Which are not surrounded by fertile
lands
Answer: d) Which are not surrounded by fertile lands
53. Is eutrophication a natural process?
a) Yes, it occurs naturally when glaciers retreat over generations. b) Yes, it
happens naturally over millennia as lakes age and sediment settles in. c) No,
all lakes are oligotrophic. d) None of the above
Answer: b) Yes, it happens naturally over millennia as lakes age and sediment
settles in.
54. The another term used for eutrophication is
a) Dystrophication b) Hypertrophication c) All of the above d) Simplifica-
tion
Answer: c) All of the above
55. Eutrophication causes aquatic species to die by
a) Building up carbon dioxide in water b) Causing Lack of nitrogen in water
c) Causing Lack of oxygen in water d) Causing lack of CO2 in water
Answer: c) Causing Lack of oxygen in water
56. DO levels fall during eutrophication because
a) It is used by bacteria to degrade organic matter. b) It is used by algae during
photosynthesis. c) It reacts with hydrogen to form water d) Aquatic plants
use it up for respiration.
Answer: a) It is used by bacteria to degrade organic matter
57. Lower BOD signifies
a) More oxygen is removed from water b) Less oxygen is removed from water
c) Water is pure d) More carbon dioxide is dissolved in water
Answer: b) Less oxygen is removed from water and c) Water is pure
58. Harmful algal bloom is caused by the algae
a) Pyrrophyta b) Rhodophyta c) Cyanobacteria d) Xanthophyta
Answer: c) Cyanobacteria

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59. The probability of
i ncreaseswhenP andN buildupa)P hytoplankton b)Dissolvedoxygen c)Oxygenation d)HigherBODAnswer:a)P hytoplan

60. A soil is composed of solid spherical grains of identical specific gravity and di-
ameter between 0.075 mm and 0.0075 mm. If the terminal velocity of largest
particle falling through water without flocculation is 0.5 mm/sec then, that for
the smallest particle would be
a) 0.005 b) 0.05 c) 5 d) 50 e) 0.0005
Answer: a) 0.005
61. In a sewage treatment system, a grit chamber of dimensions 10 m × 1.5 m × 0.75
m liquid depth liquid flow of 750 m³/h. The surface loading rate and detention
time of the grit chamber are respectively:
a) 5 m³/h/m²; 0.9 min b) 5000 l/h/m²; 9 min c) 50 m³/h/m²; 1.8 min d) 50,000
l/h/m²; 0.9 min e) 100,000 l/h/m²; 1.8 min
Answer: d) 50,000 l/h/m²; 0.9 min
62. Wastewater is treated in the sedimentation stage which is divided into four types
as shown in the figure. Match the following process of sedimentation corre-
sponding to type I, II, III, and IV against A, B, C, and D. Hindered settling, discrete
settling, compression settling, and Flocculant settling. Based on this, select the
correct option
a) A-Discrete settling, B-Flocculant settling, C-Hindered Setting, D-Compression
settling b) A-Discrete settling, B-Hindered Setting, C-Flocculant settling, D-Compression
settling c) A-Discrete settling, B-Compression settling, C-Hindered Setting, D-
Flocculant settling d) A-Flocculant settling, B-Discrete settling, C-Hindered Set-
ting, D-Compression settling e) A-Hindered Setting, B-Flocculant settling, C-
Discrete settling, D-Compression settling
Answer: a) A-Discrete settling, B-Flocculant settling, C-Hindered Setting, D-Compression
settling
63. The detention period for plain sedimentation water tank is
a) 4 to 8 hours b) 8 to 16 hours c) 16 to 24 hours d) 24 to 36 hours
Answer: d) 24 to 36 hours
64. In continuous flow sedimentation tank the quantity of water passing per hour
(or per day) per unit horizontal area is known as:
a) Overflow rate b) Both Overflow rate and Surface loading c) Surface load-
ing d) Flowing through period e) None of the above
Answer: b) Both Overflow rate and Surface loading
65. The minimum residual chlorine desired after the chlorination process?
a) 0.2 ppm b) 2 ppm c) 20 ppm d) 1 ppm
Answer: a) 0.2 ppm
66. Plain chlorination is done after
a) aeration b) sedimentation c) filtration d) softening
Answer: c) filtration
67. The only disinfectant available in the three states (i.e., solid, liquid and gas) is
a) chlorine b) bromine c) iodine d) fluorine
Answer: a) chlorine

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68. The efficiency of disinfection by chlorine, in water treatment, increases by:
a) decrease in time of contact b) decrease in temperature of water c) increase
in temperature of water d) constant temperature of water e) None of the
above
Answer: c) increase in temperature of water
69. Which one of the following is universally practised for disinfection of water?
a) Boiling b) Excess lime treatment c) Ultraviolet ray treatment d) Chlori-
nation
Answer: d) Chlorination
70. As per IS 2296-1982, which category of surface water can be used as drinking
water source without conventional treatment but after disinfection?
a) Category B b) Category C c) Category D d) Category A
Answer: d) Category A
71. Which one of the following forms of chlorine has no disinfectant property:
a) Hypochlorous acid b) Hypochlorite ion c) Monochloramine d) Trichlo-
ramine
Answer: d) Trichloramine
72. The most commonly used disinfectant for drinking water throughout the world
is
a) alum b) nitrogen c) lime d) chlorine
Answer: d) chlorine
73. Which Chloramine is formed, when the pH range is less than 4.4?
a) Monochloramine b) Dichloramine c) Both Trichloramine and Dichloramine
d) Trichloramine
Answer: d) Trichloramine
74. The chlorine demand of a water sample was found to be 0.2 mg/litre. The amount
of bleaching powder containing 30a) 0.06 mg b) 0.14 mg c) 1.33 mg d) 0.67
mg
Answer: d) 0.67 mg
75. During the purification of water, if chlorine is applied beyond the stage of break-
point, then the water is called as:
a) Double chlorinated b) Super-chlorinated c) Post chlorinated d) Pre-chlorinated
Answer: b) Super-chlorinated
76. What is the main reason for pH control during disinfection?
a) To inhibit the reaction of chlorine with water b) To ensure that powerful
residual hypochlorous acid (HOCl) is formed c) To ensure a good water pH in
the distribution system d) To ensure only HCl is formed
Answer: b) To ensure that powerful residual hypochlorous acid (HOCl) is formed
77. Dechlorination of water is achieved by adding
a) Sodium hexametaphosphate b) Sodium sulphate c) Sodium thiosulphate
d) None of the above
Answer: c) Sodium thiosulphate
78. Which one of the following is the advantage of using activated carbon for water

8
 treatment?
a) When used in powdered form after coagulation, it does not aid in coagulation.
b) It increases the chlorine demand of treated water. c) It removes organic
matter present in water. d) Its overdose is not harmful
Answer: d) Its overdose is not harmful
79. Which of the following treatments reduce salinity of water? (i) Flocculation and
sedimentation. (ii) Filtration. (iii) Reverse osmosis. (iv) Electrodialysis. Select
the correct answer given below.
a) (i) and (ii) b) (iii) and (iv) c) (ii) and (iii) d) (i) and (iv)
Answer: b) (iii) and (iv)
80. Zero hardness of water is achieved by
a) lime - soda process b) excess lime treatment c) zeolite process d) excess
alum and lime treatment
Answer: c) zeolite process
81. Temporary hardness of water is due to the presence of
a) chlorides b) carbonates c) sulphates d) nitrates
Answer: b) carbonates
82. Which of the following options causes temporary hardness of water?
a) Nitrates of calcium or magnesium b) Carbonates of calcium or magnesium
c) Sulphates of calcium or magnesium d) Chlorides of calcium or magnesium
Answer: b) Carbonates of calcium or magnesium
83. Which of the following method uses Ca(OH)2 (slaked lime) for water softening?
a) Clark’s method b) Versenate method c) Hehner’s method d) Colorimetric
method
Answer: a) Clark’s method
84. The name of the water coming out of the kitchen, bathroom, and wash basin?
a) Garbage b) Sullage c) Sewage d) Discharge
Answer: b) Sullage
85. The activated sludge process is an example of:
a) Anaerobic suspended growth process b) Anaerobic attached growth process
c) Aerobic attached growth process d) Aerobic suspended growth process
Answer: d) Aerobic suspended growth process
86. Blue baby disease found in infants is due to excessive
i ndrinkingwater.a)Colour b)Sulphates c)Carbonates d)N it

87. Sewers must be checked for minimum velocities at their minimum hourly flows
which is equal to:
a) 1/3 average daily flows b) 1/4 average daily flows c) average daily flows
d) 1/2 average daily flows
Answer: a) 1/3 average daily flows
88. Match List I with List II and select the correct answer from the combinations
given below:
List I a. Sludge volume index 1. Settling in primary sedimentation tank. b. Thick-
ening of sludge 2. Settling in secondary sedimentation tank. c. Scum removal 3.
Filtration in trickling filter. d. Recycling of effluent 4. Activated sludge process.

9
 a) a-2, b-4, c-1, d-3 b) a-4, b-2, c-3, d-1 c) a-2, b-4, c-3, d-1 d) a-4, b-2, c-1, d-3
Answer: d) a-4, b-2, c-1, d-3
89. With reference to treatment of waste water, the skimming tanks are used for:
a) removal of oil and grease b) mixing of coagulants c) removal of gases like
methane d) removal of inorganic grit
Answer: a) removal of oil and grease
90. In designing Imhoff tanks, the usual retention period is
a) 2 hours b) 20 hours c) 14 hours d) 8 hours
Answer: a) 2 hours
91. For roughing type trickling filters what would be the BOD removal rate?
a) 50 - 80Answer: b) 40 - 70
92. Which type of bacteria is used in trickling filters?
a) Facultative b) Blue-green bacteria c) Anaerobic d) Nitrifying
Answer: a) Facultative
93. The activated sludge process is an
a) Aerobic attached growth system b) Anaerobic attached growth system c)
Anaerobic suspended growth system d) Aerobic suspended system
Answer: d) Aerobic suspended system
94. Match List - I with List-II and select the correct answer using the codes given
below the lists:
List - I (Treatment Unit) A. Grit chamber i. Six hours B. Primary sedimentation
ii. Two minutes C. Activated sludge iii. Two hours D. Sludge digestion iv. Twenty
days
a) A - iii, B - i, C - iv, D - ii b) A - ii, B - iii, C - i, D - iv c) A - ii, B - i, C - iii, D - iv
d) A - i, B - ii, C - iii, D - iv
Answer: b) A - ii, B - iii, C - i, D - iv
95. What will be the Sludge Volume Index (SVI) (ml/gram) if 100 ml of sludge col-
lected in 30 mins on drying weighs 800 mg?
a) 125 b) 8 c) 0.008 d) 0.125
Answer: a) 125
96. A
t ankisanundergroundchambermadeof concrete,f iberglass,orplasticthroughwhichdomesticwastewater(sewage)f lowsf orbasictreatment.a)soap b)press

97. Which treatments reduce salinity of water? (i) Flocculation and sedimentation.
(ii) Filtration. (iii) Reverse osmosis. (iv) Electrodialysis.
a) (i) and (ii) b) (iii) and (iv) c) (ii) and (iii) d) (i) and (iv)
Answer: b) (iii) and (iv)
98. The name of the water coming out of the kitchen, bathroom, and wash basin?
a) Garbage b) Sullage c) Sewage d) Discharge
Answer: b) Sullage
99. The activated sludge process is an example of:
a) Anaerobic suspended growth process b) Anaerobic attached growth process
c) Aerobic attached growth process d) Aerobic suspended growth process
Answer: d) Aerobic suspended growth process

10
100. Blue baby disease found in infants is due to excessive
i ndrinkingwater.a)Colour b)Sulphates c)Carbonates d)N it

101. Sewers must be checked for minimum velocities at their minimum hourly flows
which is equal to:
a) 1/3 average daily flows b) 1/4 average daily flows c) average daily flows
d) 1/2 average daily flows
Answer: a) 1/3 average daily flows
102. According to the Environmental Protection Agency (EPA), which one of the fol-
lowing is the largest source of sulphur dioxide emissions?
a) Not available b) Not available c) Not available d) Not available
Answer: Not provided
103. Consider the following statements: 1) Statement I: Many chewing gums found
in the market are a source of environmental pollution. 2) Statement II: Many
chewing gums contain plastic as gum base. Which one of the following is correct
in respect of the above statements?
a) Not available b) Not available c) Not available d) Not available
Answer: Not provided
104. With reference to perfluoroalkyl and polyfluoroalkyl substances (PFAS) that are
used in making many consumer products, consider the following statements: 1)
PFAS are found to be widespread in drinking water, food and food packaging
materials. 2) PFAS are not easily degraded in the environment. 3) Persistent
exposure to PFAS can lead to bioaccumulation in animal bodies. Which of the
statements given above are correct?
a) Not available b) Not available c) Not available d) Not available
Answer: Not provided
105. Consider the following: 1. Aerosols 2. Foam agents 3. Fire retardants 4. Lubri-
cants In the making of how many of the above are hydrofluorocarbons used?
a) Not available b) Not available c) Not available d) Not available
Answer: Not provided
106. Consider the following activities: 1. Spreading finely ground basalt rock on farm-
lands extensively 2. Increasing the alkalinity of oceans by adding lime 3. Cap-
turing carbon dioxide released by various industries and pumping it into aban-
doned subterranean mines in the form of carbonated waters How many of the
above activities are often considered and discussed for carbon capture and se-
questration?
a) Not available b) Not available c) Not available d) Not available
Answer: Not provided
107. Consider the following statements regarding mercury pollution: 1. Gold mining
activity is a source of mercury pollution in the world. 2. Coal-based thermal
power plants cause mercury pollution. 3. There is no known safe level of expo-
sure to mercury. How many of the above statements are correct?
a) Not available b) Not available c) Not available d) Not available
Answer: Not provided
108. Which one of the following best describes the term “greenwashing”?
a) Not available b) Not available c) Not available d) Not available

11
 Answer: Not provided
109. In the context of WHO Air Quality Guidelines, consider the following statements:
1. The 24-hour mean of PM 2.5 should not exceed 15 µg/m³ and annual mean
of PM 2.5 should not exceed 5 µg/m³. 2. In a year, the highest levels of ozone
pollution occur during the periods of inclement weather. 3. PM 10 can penetrate
the lung barrier and enter the bloodstream. 4. Excessive ozone in the air can
trigger asthma. Which of the statements given above are correct?
a) Not available b) Not available c) Not available d) Not available
Answer: Not provided
110. Design of a circular settling tank for primary treatment of sewage with a flow
rate of 10 million liters/day, detention period of 2.0 hours, and surface loading
rate of 40000 liters/m²/day, to find the height of the water column (answer range:
3 to 3.4 meters).
a) Not available b) Not available c) Not available d) Not available
Answer: Not provided
111. Time required to remove 95a) Not available b) Not available c) Not available
d) Not available
Answer: Not provided
112. Identification of correct statements regarding water and wastewater treatments,
including effects of particulate matter, ammonia, phosphorous, calcium, and
magnesium (correct options: a, c, d).
a) Not available b) Not available c) Not available d) Not available
Answer: Not provided
113. Volume of aeration tank required for an activated sludge plant with a wastew-
ater inflow of 0.5 m³/s, food to microorganism ratio of 0.2 mg/mg-d, influent
biodegradable organic matter concentration of 150 mg/L, and mixed liquor volatile
suspended solids concentration of 2000 mg/L, assuming complete removal (an-
swer range: 16200 to 16200 m³).
a) Not available b) Not available c) Not available d) Not available
Answer: Not provided
114. Identification of waterborne diseases caused by viral pathogens (correct options:
a, c - Acute anterior poliomyelitis, Infectious hepatitis).
a) Not available b) Not available c) Not available d) Not available
Answer: Not provided
115. Calculation of ultimate BOD of sewage given a 2a) Not available b) Not avail-
able c) Not available d) Not available
Answer: Not provided
116. Design of a grit chamber to remove 0.25 mm particles with specific gravity 2.70,
terminal settling velocity of 2.5 cm/s, width of 0.50 m, peak flow of 9720 m³/d,
depth of flow 0.75 m, and flow-through velocity of 0.3 m/s, to find minimum
length (answer range: 9 to 9 m).
a) Not available b) Not available c) Not available d) Not available
Answer: Not provided

12
117. Underflow volume of sludge wastage for an activated sludge process treating
7500 m³/day municipal wastewater, with ultimate BOD of influent 200 mg/L, ef-
fluent BOD 20 mg/L, MLVSS 3000 mg/L, underflow 12000 mg/L, hydraulic reten-
tion time 0.2 days, and mean cell residence time 10 days (answer range: 37 to 38
m³/day).
a) Not available b) Not available c) Not available d) Not available
Answer: Not provided
118. Surface area of a secondary clarifier for thickening, handling 9600 m³/d from
aeration tank with solids concentration 3000 mg/L, thickened to 12000 mg/L, de-
signed for solid flux of 3.2 kg/m²·h (answer range: 375 to 375 m²).
a) Not available b) Not available c) Not available d) Not available
Answer: Not provided
119. Length of chlorination tank for disinfecting wastewater with 35 mg/L chlorine to
achieve 99a) Not available b) Not available c) Not available d) Not available
Answer: Not provided
120. Ratio of lengths LC M F R/LP F Rf orareactorwithC/C₀ = 0.8, f ollowingf irst−orderreaction, f orcom
f lowreactor(P F R)(answer : 1.12).
a)N otavailable b)N otavailable c)N otavailable d)N otavailable
Answer:N otprovided
121. Mean cell residence time for a completely mixed biological reactor with recy-
cling of solids, given flow rates and microorganism concentrations (answer: 7.5
days).
a) Not available b) Not available c) Not available d) Not available
Answer: Not provided
122. Percentage increase in filtered water produced by recovering water wasted dur-
ing backwashing and maturation in a water treatment plant with 4 filters, fil-
tration rate 200 m³/d/m², backwashing rate 1000 m³/d/m², backwashing time 15
min/day, maturation time 30 min (answer range: 7.75 to 7.95a) Not available b)
Not available c) Not available d) Not available
Answer: Not provided
123. Ratio of waste activated sludge (WAS) to green waste (GW) required to achieve
a blended C:N ratio of 20:1 on dry basis, given C and N contents (answer range:
1.6 to 1.7).
a) Not available b) Not available c) Not available d) Not available
Answer: Not provided
124. Most important type of species involved in degradation of organic matter in ac-
tivated sludge process (answer: heterotrophs, option not listed).
a) Not available b) Not available c) Not available d) Not available
Answer: Not provided
125. Which process of water treatment is done to avoid floating debris, branches,
trees, or other large particles suspended in water?
a) Primary sedimentation b) Secondary sedimentation c) Screening d) Aer-
ation
Answer: c) Screening

13
126. Which of the following water treatment process is done after filtration of water?
a) Secondary sedimentation b) Flocculation c) Primary sedimentation d)
Disinfection
Answer: d) Disinfection
127. In which of the following process earthworms decompose biodegradable solid
waste?
a) Composting b) Land fills c) Shredding d) Vermi-composting
Answer: d) Vermi-composting
128. Which of the following type of pollution is Cultural eutrophication?
a) Noise pollution b) Thermal pollution c) Soil pollution d) Water pollution
Answer: d) Water pollution
129. Which of the following flow is also called sanitary sewage?
a) Nonuniform flow b) Uniform flow c) Dry weather flow d) Storm weather
flow
Answer: c) Dry weather flow
130. The State Pollution Control Board gets the power to obtain information to per-
form its functions under
o f theW ater(P reventionandControlof P ollution)Act,1974.a)Section21 b)Section33 c)Section30 d)Section20

131. Which of the following device is used to prevent the clogging of sewer pipes?
a) Drop manhole b) Storm regulators c) Flushing tank d) Lamp hole
Answer: c) Flushing tank
132. Which of the following factor does not effect the dry weather flow?
a) Infiltration of ground water b) Population growth c) Rate of water supply
d) Temperature conditions
Answer: d) Temperature conditions
133. Which of the following is an advantage of a separate water carriage system?
a) The more uniform character of sewage b) Two sets of sewer are used c)
Get choked easily d) Difficult to clean the sewer
Answer: a) The more uniform character of sewage
134. Which of the following is biodegradable waste?
a) Paper b) Food waste c) Polythene bags d) Synthetic fiber
Answer: b) Food waste
135. Earth’s surface is covered with nearly
o f water.a)70Answer:a)70

136.
i sanelixirof lif ea)Air b)W ater c)f ood d)AlltheaboveAnswer:b)W ater

137. The volume of water on the earth is

a) 1.4 billion cu km b) 1.5 billion cu km c) 1.8 billion cu km d) 2 billion cu
km
Answer: a) 1.4 billion cu km
138.
a )67Answer:b)77

139.
a )1Answer:a)1

140.
a )40−55Answer:c)60−65

14
141. Of the total rain falls
a )57Answer:c)77

142.
o f watervapourrisesf romseasurf acea)54Answer:d)84

143. The most important natural resources, which shapes the earth’s surface and reg-
ulate our climate
a) Forest resources b) Food resources c) Land resources d) Water resources
Answer: d) Water resources
144.
a )63Answer:d)93

145. Rain water is referred as

a) Underground water b) Potable water c) River water d) None of the above
Answer: b) Potable water
146. World Water Day is celebrated on
a) March 12 b) March 22 c) March 25 d) March 30
Answer: b) March 22
147. Water scarcity is mainly caused due to
a) Over population b) Low rainfall c) Over-exploitation d) Unequal access
Answer: a) Over population
148. Water is renewable natural resource because
a) It can be reused again b) It is being recycled by human being c) It is being
renewed through reduction d) It is renewed and recharged through hydrolog-
ical cycle
Answer: d) It is renewed and recharged through hydrological cycle
149.
a retheprideof Indiaa)River b)Ocean c)Dams d)P ondsAnswer:c)Dams

150. Water harvesting is a method which

a) Increase ground water level b) Not practiced in modern days c) Has no
relation with ground water d) Decrease ground water level
Answer: a) Increase ground water level
151.
i sveryessentialf orallthesustenanceof allthelivingorganismsa)W ater b)F ood c)F orest d)AirAnswer:a)W ater

152. The U.N.Council declared

y earistheinternationalyearof f reshwatera)1973 b)1983 c)1993 d)2003Answer:d)2003

153. Most polluted river in India is

a) Yamuna b) Cavery c) Chenab d) Ganga
Answer: a) Yamuna
154. Primary source of water pollution is
a) Air pollution b) Soil pollution c) Industrial discharges d) Noise pollution
Answer: c) Industrial discharges
155. Which of the following is a common waterborne pathogen responsible for wa-
terborne diseases?
a) Mosquito b) E. coli bacteria c) Cockroach d) Flea
Answer: b) E. coli bacteria

15
156. What is the main cause of nutrient pollution in water bodies?
a) Industrial discharges b) Agricultural runoff c) Oil spills d) Radioactive
waste
Answer: b) Agricultural runoff
157. Which of the following pollutants is a result of improper disposal of electronic
waste?
a) Heavy metals b) Pesticides c) Microplastics d) Radioactive materials
Answer: a) Heavy metals
158. What is the primary function of a wastewater treatment plant?
a) Increase water pollution b) Remove pollutants from water c) Introduce
toxins into water d) Promote algal bloom
Answer: b) Remove pollutants from water
159. Which chemical is commonly used in water treatment to disinfect and kill mi-
croorganisms?
a) Chlorine b) Mercury c) Lead d) Arsenic
Answer: a) Chlorine
160. What is the term for the excessive growth of algae in water bodies due to high
nutrient levels?
a) Eutrophication b) Desalination c) Filtration d) Sedimentation
Answer: a) Eutrophication
161. Which of the following is a nonpoint source of water pollution?
a) Industrial discharge pipe b) Sewage treatment plant c) Pesticide runoff
from farmland d) Oil spill from a tanker
Answer: c) Pesticide runoff from farmland
162. What is the term for the process of removing salt and other impurities from
seawater to make it suitable for drinking?
a) Filtration b) Desalination c) Distillation d) Chlorination
Answer: b) Desalination
163. Which of the following diseases is commonly associated with contaminated wa-
ter?
a) Influenza b) Malaria c) Cholera d) Tuberculosis
Answer: c) Cholera
164. What is the major contributor to plastic pollution in oceans and water bodies?
a) Biodegradable plastics b) Composting materials c) Single-use plastics d)
Glass containers
Answer: c) Single-use plastics
165. Which gas is responsible for the acidification of water bodies when dissolved in
water?
a) Oxygen b) Carbon dioxide c) Nitrogen d) Methane
Answer: b) Carbon dioxide
166. What is the primary cause of the “Dead Zone” in water bodies?
a) Oil spills b) Excessive nutrient runoff c) Radioactive contamination d)

16
 Thermal pollution
Answer: b) Excessive nutrient runoff
167. Which international organization focuses on addressing global water pollution
and promoting sustainable water management?
a) WHO (World Health Organization) b) UNICEF (United Nations International
Children’s Emergency Fund) c) UNESCO (United Nations Educational, Scien-
tific and Cultural Organization) d) Greenpeace
Answer: c) UNESCO (United Nations Educational, Scientific and Cultural Orga-
nization)
168. What is the primary purpose of the Clean Water Act in the United States?
a) Regulating air quality b) Controlling noise pollution c) Ensuring safe drink-
ing water and regulating water pollution d) Managing soil erosion
Answer: c) Ensuring safe drinking water and regulating water pollution
169. Which of the following is a common method of preventing oil spills in water
bodies?
a) Oil drilling b) Double-hulled tankers c) Disposal of oil rigs d) Increasing
oil production
Answer: b) Double-hulled tankers
170. What is the term for the process of removing suspended particles from water by
allowing them to settle?
a) Filtration b) Sedimentation c) Desalination d) Chlorination
Answer: b) Sedimentation
171. Which of the following pollutants can disrupt the endocrine system in aquatic
organisms?
a) Heavy metals b) Radioactive substances c) Endocrine-disrupting chemi-
cals d) Oxygen
Answer: c) Endocrine-disrupting chemicals
172. What is the term for the process of removing suspended particles from water by
allowing them to settle?
a) Filtration b) Sedimentation c) Desalination d) Chlorination
Answer: b) Sedimentation
173. What is the primary purpose of the Clean Water Act in the United States?
a) Regulating air quality b) Controlling noise pollution c) Ensuring safe drink-
ing water and regulating water pollution d) Managing soil erosion
Answer: c) Ensuring safe drinking water and regulating water pollution
174. Which of the following is a common method of preventing oil spills in water
bodies?
a) Oil drilling b) Double-hulled tankers c) Disposal of oil rigs d) Increasing
oil production
Answer: b) Double-hulled tankers
175. Which of the following pollutants can disrupt the endocrine system in aquatic
organisms?
a) Heavy metals b) Radioactive substances c) Endocrine-disrupting chemi-

17
 cals d) Oxygen
Answer: c) Endocrine-disrupting chemicals
176. The term for the process of removing suspended particles from water by allow-
ing them to settle is
a) Filtration b) Sedimentation c) Desalination d) Chlorination
Answer: b) Sedimentation
177. Which international organization focuses on addressing global water pollution
and promoting sustainable water management?
a) WHO b) UNICEF c) UNESCO d) Greenpeace
Answer: c) UNESCO
178. What is the major contributor to plastic pollution in oceans and water bodies?
a) Biodegradable plastics b) Composting materials c) Single-use plastics d)
Glass containers
Answer: c) Single-use plastics
179. Which gas is responsible for the acidification of water bodies when dissolved in
water?
a) Oxygen b) Carbon dioxide c) Nitrogen d) Methane
Answer: b) Carbon dioxide
180. What is the primary cause of the “Dead Zone” in water bodies?
a) Oil spills b) Excessive nutrient runoff c) Radioactive contamination d)
Thermal pollution
Answer: b) Excessive nutrient runoff
181. Which of the following diseases is commonly associated with contaminated wa-
ter?
a) Influenza b) Malaria c) Cholera d) Tuberculosis
Answer: c) Cholera
182. What is the term for the process of removing salt and other impurities from
seawater to make it suitable for drinking?
a) Filtration b) Desalination c) Distillation d) Chlorination
Answer: b) Desalination
183. Which of the following is a nonpoint source of water pollution?
a) Industrial discharge pipe b) Sewage treatment plant c) Pesticide runoff
from farmland d) Oil spill from a tanker
Answer: c) Pesticide runoff from farmland
184. What is the term for the excessive growth of algae in water bodies due to high
nutrient levels?
a) Eutrophication b) Desalination c) Filtration d) Sedimentation
Answer: a) Eutrophication
185. Which chemical is commonly used in water treatment to disinfect and kill mi-
croorganisms?
a) Chlorine b) Mercury c) Lead d) Arsenic
Answer: a) Chlorine

18
186. What is the primary function of a wastewater treatment plant?
a) Increase water pollution b) Remove pollutants from water c) Introduce
toxins into water d) Promote algal bloom
Answer: b) Remove pollutants from water
187. Which of the following pollutants is a result of improper disposal of electronic
waste?
a) Heavy metals b) Pesticides c) Microplastics d) Radioactive materials
Answer: a) Heavy metals
188. What is the main cause of nutrient pollution in water bodies?
a) Industrial discharges b) Agricultural runoff c) Oil spills d) Radioactive
waste
Answer: b) Agricultural runoff
189. Which of the following is a common waterborne pathogen responsible for wa-
terborne diseases?
a) Mosquito b) E. coli bacteria c) Cockroach d) Flea
Answer: b) E. coli bacteria
190. What is the primary source of water pollution?
a) Air pollution b) Soil pollution c) Industrial discharges d) Noise pollution
Answer: c) Industrial discharges
191. The U.N.Council declared
y earistheinternationalyearof f reshwatera)1973 b)1983 c)1993 d)2003Answer:d)2003

192.
i sveryessentialf orallthesustenanceof allthelivingorganismsa)W ater b)F ood c)F orest d)AirAnswer:a)W ater

193. Water harvesting is a method which

a) Increase ground water level b) Not practiced in modern days c) Has no
relation with ground water d) Decrease ground water level
Answer: a) Increase ground water level
194.
a retheprideof Indiaa)River b)Ocean c)Dams d)P ondsAnswer:c)Dams

195. Water is renewable natural resource because

a) It can be reused again b) It is being recycled by human being c) It is being
renewed through reduction d) It is renewed and recharged through hydrolog-
ical cycle
Answer: d) It is renewed and recharged through hydrological cycle
196. Water scarcity is mainly caused due to
a) Over population b) Low rainfall c) Over-exploitation d) Unequal access
Answer: a) Over population
197. World Water Day is celebrated on
a) March 12 b) March 22 c) March 25 d) March 30
Answer: b) March 22
198. Rain water is referred as
a) Underground water b) Potable water c) River water d) None of the above
Answer: b) Potable water
199.
a )63Answer:d)93

19
200. Of the total rain falls
a )57Answer:c)77

201.
o f watervapourrisesf romseasurf acea)54Answer:d)84

202. The most important natural resources, which shapes the earth’s surface and reg-
ulate our climate
a) Forest resources b) Food resources c) Land resources d) Water resources
Answer: d) Water resources
203.
a )40−55Answer:c)60−65

204. The volume of water on the earth is

a) 1.4 billion cu km b) 1.5 billion cu km c) 1.8 billion cu km d) 2 billion cu
km
Answer: a) 1.4 billion cu km
205.
a )67Answer:b)77

206.
a )1Answer:a)1

207. Earth’s surface is covered with nearly

o f water.a)70Answer:a)70

208.
i sanelixirof lif ea)Air b)W ater c)f ood d)AlltheaboveAnswer:b)W ater

209. Which of the following is not a water borne disease?

a) Cholera b) Typhoid c) Diarrhoea d) Malaria
Answer: d) Malaria
210. Alkalinity in water is expressed as milligrams per litre in terms of equivalent:
a) Calcium carbonate b) Magnesium carbonate c) Sodium carbonate d)
Sodium bicarbonate
Answer: a) Calcium carbonate
211. Soluble organics in sewage includes:
a) Carbohydrates b) Proteins c) Lipids d) All of the above
Answer: d) All of the above
212. The reference pressure used in the determination of sound pressure level is:
a) 20 µPa b) 20 dB c) 10 µPa d) 40 dB
Answer: a) 20 µPa
213. A city supply of 15000 cubic meters of water per day is treated with a chlorine
dosage of 0.5 ppm. For this purpose, the requirement of 25a) 300 kg b) 30 kg
c) 3 kg d) 0.3 kg
Answer: b) 30 kg
214. 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 sewer
Answer: b) Out-fall sewer
215. The device used for the easy separation of dry dust of 10 to 100 μm size is
. a)Cyclone b)Gravitysettlingcham

216. pH of water sample containing 0.1008 g of H+ ion per litre is:

a) 3 b) 4 c) 5 d) 6

20
 Answer: b) 4
217. The oxygen sag curve of a river represents:
a) BOD b) COD c) TOC d) DO
Answer: a) BOD
218. The minimum width of a septic tank is taken
. a)70cm b)75cm c)80cm d)90cmAnswer:b)75cm

21