Environmental Engineering MCQs : This section focuses on the "Environmental Engineering". These Multiple Choice Questions (MCQs) should be practiced to improve the Environmental Engineering skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.
Question 1
Ground water is usually free from
A. Suspended impurities
B. Dissolved impurities
C. Both suspended and dissolved impurities
D. None of the above
Question 2
Siderosis is a disease caused by the inhalation of __________ dust.
A. coal
B. silica
C. iron
D. none of these
Question 3
Which of the following unit works in anaerobic conditions?
A. Sludge digestion tank
B. Sedimentation tank
C. Activated sludge treatment
D. Trickling filters
Question 4
Exposure to chemicals having carcinogenic properties cause
A. dermatitis (skin disorder)
B. cancer
C. asphyxiation (suffocation)
D. asthma
Question 5
Polluted water having low BOD are most economically treated in
A. sedimentation tanks
B. oxidation ponds
C. sludge digester
D. clarifier
Question 6
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
Question 7
The amount of coagulant needed for coagulation of water increases with (i) Increase in turbidity of water (ii) Decrease in turbidity of water (iii) Increase in temperature of water (iv) Decrease in temperature of waterThe correct answer is
A. (i) and (ii)
B. (i)and(iv)
C. (ii) and (iii)
D. (ii) and (iv)
Question 8
Aerodynamic noise resulting from turbulent gas flow is the most prevalent source of valve noise in fluid ilow control. It is caused due to
A. Reynold stresses
B. shear forces
C. both (a) & (b)
D. neither (a) nor (b)
Question 9
As compared to shallow wells, deep wells have
A. More depth
B. Less depth
C. More discharge
D. Less discharge
Question 10
Select the 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)
Question 11
Which of the following chemical compounds can be used for de-chlorination of water?
A. Carbon dioxide
B. Bleaching powder
C. Sulphur dioxide
D. Chloramines
Question 12
Particulates (< 1μm size) remaining suspended in air indefinitely and transported by wind currents are called
A. fumes
B. mists
C. smoke
D. aerosols
Question 13
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
Question 14
TLV of ozone (O3) and phosgene (COCl2) in air is __________ ppm.
A. 0.1
B. 25
C. 100
D. 1000
Question 15
The settling velocity of a particle in 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
Question 16
Dust collection efficiency of a cyclone separator depends upon its
A. diameter.
B. inlet gas velocity.
C. overall height.
D. all (a), (b) & (c).
Question 17
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
Question 18
To test turbidity of polluted water in the field, _________ is used.
A. Baylis Turbidimeter
B. Jackson Turbidimeter
C. Turbidity tube
D. Turbidity rod
Question 19
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 buildings like pools, hotels etc swimming
D. All of the above
Question 20
Most of the atmospheric air pollutants are present in large quantity in
A. stratosphere
B. thermosphere
C. trophosphere
D. mesosphere
Question 21
The self cleansing velocity for all 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
Question 22
The rate of BOD exerted at any time is
A. Directly proportional to BOD satisfied
B. Directly proportional to BOD remaining
C. Inversely proportional to BOD satisfied
D. Inversely proportional to BOD remaining
Question 23
The characteristics of fresh and septic sewage respectively are
A. Acidic and alkaline
B. Alkaline and acidic
C. Both acidic
D. Both alkaline
Question 24
Pick out the wrong statement.
A. The concentric atmosphere layer just above troposphere is called stratosphere, which is rich in ozone.
B. Mesosphere is characterised by very low atmospheric pressure and low temperature.
C. Troposhere is a dusty zone containing water vapor and clouds.
D. The radio waves used in the long distance radio communication are reflected back to earth by stratosphere.
Question 25
For a country like India, where rainfall 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
Question 26
Noise level heard at a distance of about 100 metres from a jet engine with after burner is about __________ decibels.
A. 120
B. 140
C. 170
D. 200
Question 27
Bag filter design is predominantly dependent on gas temperature, as it affects the gas density & viscosity and the selection of filtering material. The pressure drop in a bag filter is
A. inversely proportional to viscosity of gas.
B. proportional to the viscosity & density of the gas.
C. proportional to the pressure of the gas.
D. both (b) and (c).
Question 28
If the time of concentration is 9 minutes, then the intensity of rainfall 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
Question 29
The ratio of 5 day BOD to ultimate BOD is about
A. 1-3
B. 2-3
C. 3-4
D. 1
Question 30
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) Back washing in rapid sand filtersThe correct answer is
A. (i) and (ii)
B. (ii) and (iii)
C. (i) and (iv)
D. (ii) and (iv)
Question 31
In 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 5 day incubation at 20°C. The BOD of raw sewage will be
A. 100 ppm
B. 200 ppm
C. 300 ppm
D. 400 ppm
Question 32
The amount of residual chlorine left in public water supply for safety against pathogenic bacteria is 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
Question 33
As compared to cast iron pipes, steel pipes are
A. Heavier
B. Stronger
C. Costlier
D. Less susceptible to corrosion
Question 34
Generally the detention period for grit chambers is kept as
A. 1 minute
B. 5 minutes
C. 24 hours
D. 12 hours
Question 35
The treatment of water with bleaching powder is known as
A. Pre-chlorination
B. Super chlorination
C. De-chlorination
D. Hypo-chlorination
Question 36
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
Question 37
The commonest form of iron & manganese found in ground water as pollutant is in the form of their
A. carbonates
B. bi-carbonates
C. chlorides
D. sulphides
Question 38
Tri-sodium phosphate is used in boiler water treatment to reduce
A. turbidity
B. caustic embrittlement
C. suspended silica
D. dissolved oxygen
Question 39
Suspended solid present in the waste water generated in blast furnace gas cooling and cleaning plant is removed by
A. biological oxygen pond.
B. radial settling tank (thickener) using coagulant (lime & ferrous sulphate).
C. lagoons.
D. filtration.
Question 40
In facultative stabilization pond, the sewage is treated by
A. Aerobic bacteria only
B. Algae only
C. Dual action of aerobic bacteria and anaerobic bacteria
D. Sedimentation
Question 41
When some chemical is mixed with water, _________ is formed.
A. Solution
B. Floc
C. Bubbles
D. Foam
Question 42
Threshold Limit Value (TLV) is the maximum allowable concentration (i.e. safe limit) of pollutants in air. Safe limit for SO2 in air is __________ ppm.
A. 5
B. 500
C. 1000
D. 2000
Question 43
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
Question 44
Which of the following is not a water borne disease?
A. Dysentery
B. Cholera
C. Typhoid
D. Malaria
Question 45
For normal sludge, the value of sludge index for Indian conditions is
A. 0 to 50
B. 50 to 150
C. 150 to 350
D. 350 to 500
Question 46
The per capital consumption of a locality is affected by (i) Climatic conditions (ii) Quality of water (iii) Distribution pressure
A. Only (i)
B. Both (i) and (ii)
C. Both (i) and (iii)
D. All (i), (ii) and (iii)
Question 47
80% less than 200 mesh size particles are called
A. smoke
B. powder
C. grit
D. aggregates
Question 48
The biochemical treatment of sewage effluents is essentially a process of
A. Oxidation
B. Dehydration
C. Reduction
D. Alkalinization
Question 49
In chlorination, with the rise in temperature of water, death rate of bacteria
A. Increases
B. Decreases
C. Remains unaffected
D. None of the above
Question 50
Presence of excess flourine in water causes
A. dental cavity
B. tooth decay
C. fluorosis
D. respiratory disease
Question 51
Main pollutants released from iron & steel industry is
A. CO, CO2 & SO2.
B. H2S, NO & SO3.
C. CO2, H2S & NO2.
D. SO3, NO2 & CO2.
Question 52
'Pneumoconiosis' is a disease caused by the inhalation of __________ dust.
A. coal
B. uranium ore
C. iron ore
D. lime
Question 53
Inhalation of lead compounds present in the automobile exhausts (using leaded petrol) causes
A. blood poisoning.
B. anaemia.
C. nervous system disorder.
D. all (a), (b) and (c).
Question 54
The specific gravity of sewage is
A. Much greater than 1
B. Slightly less than 1
C. Equal to 1
D. Slightly greater than 1
Question 55
Fluorosis (a bone disease) is caused by the presence of high concentration of __________ in atmospheric air.
A. hydrocarbons
B. hydrogen flouride
C. hydrogen sulphides
D. nitrogen dioxide
Question 56
What are the main constituents of the environmental cycles?
A. Water cycle and food cycle
B. Water cycle and nutrient cycle
C. Nutrient cycle
D. Water cycle and air cycle
Question 57
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
Question 58
The minimum dissolved oxygen which should always be present in water in order to save the aquatic life is
A. 1 ppm
B. 4 ppm
C. 10 ppm
D. 40 ppm
Question 59
A pipe conveying sewage from plumbing system of a single building to common sewer or point of immediate disposal is called
A. House sewer
B. Lateral sewer
C. Main sewer
D. Sub-main sewer
Question 60
The ratio of oxygen available to the oxygen required for stabilisation of sewage is called the
A. bacterial stability factor.
B. relative stability.
C. biological oxygen demand (BOD).
D. oxygen ion concentration.
Question 61
A pipe which is installed in the house drainage to preserve the water seal of traps is called
A. Vent pipe
B. Anti-siphonage pipe
C. Waste pipe
D. Soil pipe
Question 62
Replenishment of dissolved oxygen in water stream polluted with industrial waste occurs by
A. natural aeration of water stream.
B. photosynthetic action of algae.
C. both (a) & (b).
D. neither (a) nor (b).
Question 63
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
Question 64
As compared to rapid sand filters, slow sand filters give (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)
Question 65
The process of 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
Question 66
Disinfection of water results in
A. Removal of turbidity
B. Removal of hardness
C. Killing of disease bacteria
D. Complete sterilisation
Question 67
Which of the following sewers is preferred for combined system of sewage?
A. Circular sewer
B. Egg shaped sewer
C. Rectangular sewer
D. None of the above
Question 68
Which of the below leads to disturbance of nitrogen fixation in the soil?
A. Urban waste
B. Fertilizers
C. Pesticides
D. Industrial effluents
Question 69
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 inorganic solids
D. Bacteria and colloidal solids
Question 70
Aerobic biological oxidation ponds used for the purification of polluted water
A. destroys/removes pathogen from the sewage.
B. is not very effective for nonbiodegradable substances (e.g. ABS) containing effluents.
C. destroys/removes pathogen much more effectively if the sewage is chlorinated.
D. all (a), (b) & (c).
Question 71
Corrosion in concrete sewers is caused by
A. Septic conditions
B. Dissolved oxygen
C. Chlorine
D. Nitrogen
Question 72
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
Question 73
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
Question 74
Which of the following dust collection equipments is the least efficient (for sub-micronic particles) ?
A. Dust catcher (gravity type)
B. Cyclone separator
C. Bag filter
D. Hollow wet scrubber
Question 75
The main pollutant in waste water discharged from a petroleum refinery is oil (both in free and emulsified form). Free oil is removed by
A. biological oxygen pond.
B. aerated lagoons.
C. trickling filters.
D. gravity separator having oil skimming devices.
Question 76
Sewage treatment units are normally designed for
A. 5 - 10 years
B. 15 - 20 years
C. 30 - 40 years
D. 40 - 50 years
Question 77
When there is no recirculation of sewage, then recirculation factor is
A. 0
B. 1
C. Infinity
D. None of the above
Question 78
The maximum discharge of a tube well is about
A. 5 liters/sec
B. 50 liters/sec
C. 500 liters/sec
D. 1000 liters/sec
Question 79
Which of the following compounds is widely used for algae control?
A. Sodium sulphate
B. Copper sulphate
C. Sodium chloride
D. Calcium chloride
Question 80
An egg shaped section of 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
Question 81
The percentage of chlorine in fresh bleaching powder is about
A. 10 to 15
B. 20 to 25
C. 30 to 35
D. 40 to 50
Question 82
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
Question 83
Alkalinity in water is expressed as milligrams per litre in terms of equivalent
A. Calcium carbonate
B. Magnesium carbonate
C. Sodium carbonate
D. Calcium hydroxide
Question 84
Activated carbon is used for
A. Disinfection
B. Removing hardness
C. Removing odours
D. Removing corrosiveness
Question 85
The overflow rate for plain sedimentation tanks is about
A. 500 to 750 liters/hour/ m²
B. 1000 to 1250 liters/hour/ m²
C. 1250 to 1500 liters/hour/m²
D. 1500 to 2000 liters/hour/m²
Question 86
The widest explosive limit is of __________ , thereby making it the most explosive gas.
A. acetylene
B. petrol vapor
C. hydrogen
D. carbon monoxide
Question 87
In 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
Question 88
Septic tank is a (i) Settling tank (ii) Digestion tank (iii) Aeration tank
A. Only (i)
B. (i) and (ii)
C. (i) and (iii)
D. Only (iii)
Question 89
Disinfection efficiency is
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
Question 90
The gas from sludge digestion tank is mainly composed of
A. Nitrogen
B. Carbon dioxide
C. Hydrogen sulphide
D. Methane
Question 91
Residual chlorine in water is determined by
A. Starch iodide method
B. Orthotolidine method
C. Both (A) and (B)
D. None of the above
Question 92
Ionisation potential employed in the industrial electrostatic precipitator is of the order of
A. 30 to 70 kV DC
B. 30 to 70 kV AC
C. 230 V AC
D. 230 V DC
Question 93
Tolerable limit of nitrogen oxides in air is __________ ppm.
A. 0.1
B. 1
C. 5
D. 25
Question 94
Pick out the wrong statement.
A. Caustic embrittlement of boiler's metallic parts is caused by high concentration of caustic soda in boiler feed water.
B. Cooling and freezing of water kills the bacteria present in it.
C. With increasing boiler operating pressure of steam, the maximum allowable concentration of silica in feed water goes on decreasing.
D. Dissolved oxygen content in high pressure boiler feed water should be nil.
Question 95
Which of the following pollutants is not emitted during volcanic eruptions ?
A. SO2
B. H2S
C. CO
D. hydrocarbons
Question 96
Air binding 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
Question 97
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
Question 98
Operating principle of cyclone separator is based on the action of __________ dust particles.
A. diffusion of
B. centrifugal force on
C. gravitational force on
D. electrostatic force on
Question 99
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
Question 100
The distribution mains are designed for
A. Maximum daily demand
B. Maximum hourly demand
C. Average daily demand
D. Maximum hourly demand on maximum day
Question 101
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
Question 102
Pollution cases can be classified into _________ types.
A. 4
B. 2
C. 5
D. 6
Question 103
Dissolved oxygen in streams is
A. Maximum at noon
B. Minimum at noon
C. Maximum at midnight
D. Same throughout the day
Question 104
_________ is the simplest equipment used for collection of solid particulates.
A. Inertial separators
B. Filters
C. Settling chamber
D. Cyclones
Question 105
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
Question 106
Which is a secondary air pollutant ?
A. Photochemical smog
B. Sulphur dioxide
C. Nitrogen dioxide
D. Dust particles
Question 107
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
Question 108
The suitable method of 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
Question 109
Iron & manganese present as pollutant in water can not be removed by
A. ion exchange process.
B. oxidation followed by settling & filtration.
C. lime soda process or manganese zeolite process.
D. chlorination.
Question 110
Hardy cross method of analysis of distribution system (i) Involves successive trials (ii) Takes economic aspects into account (iii) Is time consuming
A. Only (i)
B. (i) and (ii)
C. (i) and (iii)
D. All are correct
Question 111
The devices which are installed for drawing water from the sources are called
A. Aquifers
B. Aquiclude
C. Filters
D. Intakes
Question 112
Which of the following is the common pollutant emitted from metallurgical smelters, thermal power plant and cement plants ?
A. NOx
B. Hg
C. SO2
D. F
Question 113
Orthotolidine test is used for determination of
A. Dissolved oxygen
B. Residual chlorine
C. Biochemical oxygen demand
D. Dose of coagulant
Question 114
Sewage treatment units are designed for
A. Maximum flow only
B. Minimum flow only
C. Average flow only
D. Maximum and minimum flow
Question 115
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 (iii) Completed coli-form test
A. Only (i)
B. Both (i) and (ii)
C. Both (i) and (iii)
D. All (i), (ii) and (iii)
Question 116
_________ is a raw material sent to and processed in a waste recycling plant.
A. Recyclant
B. Nodules
C. Particulars
D. Recyclate
Question 117
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
Question 118
Which of the following is the most detrimental for water used in high pressure boiler ?
A. Silica
B. Turbidity
C. Phenol
D. Dissolved oxygen
Question 119
Turbidity of water is an indication of the presence of
A. suspended inorganic matter
B. dissolved solids
C. floating solids
D. dissolved gases
Question 120
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
Question 121
Smoke is produced due to
A. insufficient supply of combustion air and insufficient time for combustion.
B. poor quality of fuel and improper mixing of fuel & combustion air.
C. poor design & overloading of furnace.
D. all (a), (b) and (c).
Question 122
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
Question 123
The effective size of sand particles used in slow sand filters is
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
Question 124
Coal washing waste water containing about 3% suspended solids (comprising of clay, slate, stone etc.) is treated for solid particles removal
A. by chemical coagulation.
B. in sedimentation tanks equipped with mechanical scrapper.
C. in vacuum filter.
D. in clarifiers.
Question 125
Which of the following values of pH represents a stronger acid?
A. 2
B. 5
C. 7
D. 10
Question 126
Laying of sewers is usually done with the help of
A. A Theodolite
B. A compass
C. Sight rails and boning rods
D. A plane table
Question 127
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 mains
Question 128
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 chlorine in water
Question 129
The type of sewer which is suitable for both combined and separate system is
A. Circular sewer
B. Egg shaped sewer
C. Horseshoe type sewer
D. Semi-elliptical sewer
Question 130
Inhalation of lead compounds present in automobile exhaust (using leaded petrol) causes
A. blood poisoning.
B. anaemia.
C. nervous system disorder.
D. all (a), (b) & (c).
Question 131
The suitable layout of a distribution system for irregularly growing town is
A. Dead end system
B. Grid iron system
C. Radial system
D. Ring system
Question 132
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
Question 133
Which of the following retards the self purification of stream?
A. Higher temperature
B. Sunlight
C. Satisfying oxygen demand
D. None of the above
Question 134
The maximum efficiency of BOD removal is achieved in
A. Oxidation pond
B. Oxidation ditch
C. Aerated lagoons
D. Trickling filters
Question 135
In water chemical treatment plant, use of chloramines ensures
A. disinfection.
B. taste & odour control.
C. weed control in reservoirs.
D. removal of permanent hardness.
Question 136
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
Question 137
Settling velocity increases with
A. Specific gravity of solid particles
B. Size of particles
C. Depth of tank
D. Temperature of liquid
Question 138
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
Question 139
The layout of distribution system in which water flows towards the outer periphery is
A. Ring system
B. Dead end system
C. Radial system
D. Grid iron system
Question 140
Hydrogen Peroxide is generated from:
A. Photochemical smog products
B. Explosive manufacturing industry
C. Automobile exhausts
D. Thermal power plants
Question 141
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
Question 142
Chlorine demand of water is equal to
A. Applied chlorine
B. Residual chlorine
C. Sum of applied and residual chlorine
D. Difference of applied and residual chlorine
Question 143
If the sewage contains grease and fatty oils, these are removed in
A. Grit chambers
B. Detritus tanks
C. Skimming tanks
D. Sedimentation tanks
Question 144
The dissolved oxygen level in natural unpolluted waters at normal temperature is found to be of the order of
A. 1 mg/liter
B. 10 mg/liter
C. 100 mg/liter
D. 1000 mg/liter
Question 145
Assertion A: Slow sand filters are more efficient in removal of bacteria than rapid sand filters.Reason R: The sand used in slow sand filters is finer than that in rapid sand filtersSelect your answer based on 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
Question 146
The means of access for inspection and cleaning of sewer line is known as
A. Inlet
B. Manhole
C. Drop manhole
D. Catch basin
Question 147
Standard BOD is measured at
A. 20°C - 1 day
B. 25°C - 3 day
C. 20°C - 5 day
D. 30°C - 5 day
Question 148
The presence of gas in water is indicated by:
A. Fizzing sound
B. Foam
C. Bubbles
D. Colour change
Question 149
The design discharge for the separate sewer system shall be taken as
A. Equal to dry weather flow (DWF)
B. 2 × DWF
C. 3 × DWF
D. 6 × DWF
Question 150
As compared to higher pH values, the contact period required for efficient chlorination at lower pH values is
A. Smaller
B. Larger
C. Same
D. None of the above
Question 151
The disinfection efficiency of chlorine increases by (i) Decreasing the time of contact (ii) Decreasing the temperature of water (iii) Increasing the temperature of water
A. Only (i)
B. Both (i) and (ii)
C. Both (i) and (iii)
D. Only (iii)
Question 152
Sewerage system is usually designed for
A. 10 years
B. 25 years
C. 50 years
D. 75 years
Question 153
Turbidity is measured on
A. Standard silica scale
B. Standard cobalt scale
C. Standard platinum scale
D. Platinum cobalt scale
Question 154
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
Question 155
Phenolic water generated in coke ovens & by-product plant attached to an integrated steel plant containing phenol in concentration of less than 100 mg/litre can be removed by
A. chlorination
B. treating in biological oxygen pond
C. chemical coagulation
D. none of these
Question 156
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
Question 157
The process in which the chlorination is done beyond the break point is known as
A. Pre-chlorination
B. Post chlorination
C. Super chlorination
D. Break point chlorination
Question 158
Persons working in cement plants and limestone quarries are more prone to disease like
A. cancer
B. asthma
C. silicosis
D. flourosis (bone disease)
Question 159
Maximum allowable concentration of CO2 in air for safe working is __________ ppm (parts per million).
A. 50
B. 1000
C. 2000
D. 5000
Question 160
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
Question 161
Scale formation in boiler is controlled by
A. preheating of feed water.
B. reduction in hardness, silica & alumina in feed water.
C. keeping the pH value of feed water just below 7.
D. eliminating H2S in feed water.
Question 162
For the same solid content, if the quantity of sludge with moisture content of 98% is X, then the quantity of sludge with moisture content of 96% will be
A. X/4
B. X/2
C. X
D. 2X
Question 163
Which is the best and the most effective method for the removal of organic contaminant present in the polluted water in very small quantity (say < 200 mg/litre)?
A. Lagooning
B. Activated carbon adsorption
C. Biological oxidation pond
D. Chemical coagulation
Question 164
The detention period for oxidation ponds is usually kept as
A. 48 hours
B. 24 hours
C. 10 to 15 days
D. 3 months
Question 165
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
Question 166
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. Reinforced cement concrete
Question 167
The polluted water is one which
A. Contains 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
Question 168
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
Question 169
During which of the following operating conditions of an automobile, carbon monoxide content in the exhaust gas is maximum ?
A. Idle running
B. Acceleration
C. Cruising
D. Deaccelaration
Question 170
On standard silica scale, the turbidity in drinking water should be limited to
A. 10 ppm
B. 20 ppm
C. 30 ppm
D. 50 ppm
Question 171
Most suitable section of sewer in separate sewage system is
A. Rectangular section
B. Circular section
C. Standard form of egg shaped sewer
D. Modified egg shaped section
Question 172
The detention period and overflow rate respectively for plain sedimentation as compared to sedimentation with coagulation are generally
A. Less and more
B. Less and less
C. More and less
D. More and more
Question 173
The type of valve, which is provided on the suction pipe in a tube-well, is
A. Air relief valve
B. Reflux valve
C. Pressure relief valve
D. Sluice valve
Question 174
The maximum permissible limit for fluoride in drinking water is
A. 0.1 mg/liter
B. 1.5 mg/liter
C. 5 mg/liter
D. 10 mg/liter
Question 175
Period of cleaning of slow sand filters is about
A. 24 - 48 hours
B. 10 - 12 days
C. 2 - 3 months
D. 1 - 2 year
Question 176
The most common cause of acidity in water is
A. Carbon dioxide
B. Oxygen
C. Hydrogen
D. Nitrogen
Question 177
Composting and lagooning are the methods of
A. Sludge digestion
B. Sludge disposal
C. Sedimentation
D. Filtration
Question 178
The time of concentration is defined as
A. The time taken by rainfall water to run from most distant point of water shed to the inlet of sewer
B. The time required for flow of water in sewer to the point under consideration
C. Sum of (A) and (B)
D. Difference of (A) and (B)
Question 179
Sewerage system is designed for
A. Maximum flow only
B. Minimum flow only
C. Average flow only
D. Maximum and minimum flow
Question 180
A sewer that receives the discharge of a number of house sewers is called
A. House sewer
B. Lateral sewer
C. Intercepting sewer
D. Sub-main sewer
Question 181
Failures within hydrosphere in oxygen cycle can result in the development of:
A. Hyperoxic zones
B. Hypoxic zones
C. Hydrolic zones
D. Hydroxic zones
Question 182
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
Question 183
The living environment, the biosphere consists of __________ components.
A. 2
B. 4
C. 1
D. 3
Question 184
The rate of Alteration of pressure filters is
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
Question 185
The suitable system of sanitation for area of distributed rainfall throughout the year with less intensity is
A. Separate system
B. Combined system
C. Partially separate system
D. Partially combined system
Question 186
The pathogens can be killed by
A. Nitrification
B. Chlorination
C. Oxidation
D. None of the above
Question 187
Most of the bacteria in sewage are
A. Parasitic
B. Saprophytic
C. Pathogenic
D. Anaerobic
Question 188
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
Question 189
The design discharge for the combined sewer system shall be taken as
A. Equal to rainfall
B. Rainfall + DWF
C. Rainfall + 2 DWF
D. Rainfall + 6 DWF
Question 190
Exposure to small amount of __________ results in high blood pressure & heart disease in human beings.
A. hydrogen sulphide
B. mercury
C. cadmium
D. asbestos
Question 191
The chemical most commonly used to increase speed of sedimentation of sewage is
A. Sulphuric acid
B. Copper sulphate
C. Lime
D. Sodium permanganate
Question 192
Which of the following methods of analysis of water distribution system is most suitable for long and narrow pipe system?
A. Circle method
B. Equivalent pipe method
C. Hardy cross method
D. Electrical analysis method
Question 193
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
Question 194
The suitable layout of distribution system for a city with roads of rectangular pattern is
A. Grid iron system
B. Dead end system
C. Ring system
D. Radial system
Question 195
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
Question 196
The main disadvantage of 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
Question 197
H2S present in gaseous stream can be removed by adsorption on
A. silica gel
B. active carbon
C. bog iron
D. limestone powder
Question 198
In the method of trenching, the size of the trench may be:
A. 12 x 5 x 2m
B. 15 x 5 x 3m
C. 12 x 3 x 2m
D. 15 x 5 x 5m
Question 199
Select the correct statement.
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
Question 200
The detention period in coagulation tanks is usually kept as
A. 1 to 2 minutes
B. 30 to 45 minutes
C. 2 to 6 hours
D. 2 to 6 days
Question 201
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
Question 202
Average rate of water consumption per head per day as per Indian Standard is
A. 100 liters
B. 135 liters
C. 165 liters
D. 200 liters
Question 203
The hourly variation factor is usually taken as
A. 1.5
B. 1.8
C. 2
D. 2.7
Question 204
The relative stability of a sewage sample, whose dissolved oxygen is same as the total oxygen required to satisfy BOD, is
A. 1
B. 100
C. Infinite
D. Zero
Question 205
The hydraulic mean depth (HMD) for an egg-shaped sewer 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
Question 206
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
Question 207
The depression of water table in a well due to pumping will be maximum(Where ‘R’ is the radius of influence)
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
Question 208
If the average daily consumption of a city is 100,000 m³, the maximum daily consumption on peak hourly demand will be
A. 100000 m³
B. 150000 m³
C. 180000 m³
D. 270000 m³
Question 209
TLV of mercury in potable (drinking) water is about __________ ppm.
A. 0.001
B. 0.1
C. 1
D. 5