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Environmental Engineering MCQ Questions & Answers

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

80% less than 200 mesh size particles are called

A. smoke
B. powder
C. grit
D. aggregates

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Question 2

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).

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Question 3

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)

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Question 4

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).

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Question 5

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.

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Question 6

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

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Question 7

Dust collection efficiency of a cyclone separator depends upon its

A. diameter.
B. inlet gas velocity.
C. overall height.
D. all (a), (b) & (c).

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Question 8

Exposure to chemicals having carcinogenic properties cause

A. dermatitis (skin disorder)
B. cancer
C. asphyxiation (suffocation)
D. asthma

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Question 9

Exposure to small amount of __________ results in high blood pressure & heart disease in human beings.

A. hydrogen sulphide
B. mercury
C. cadmium
D. asbestos

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Question 10

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

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Question 11

H2S present in gaseous stream can be removed by adsorption on

A. silica gel
B. active carbon
C. bog iron
D. limestone powder

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Question 12

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.

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Question 13

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).

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Question 14

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).

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Question 15

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

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Question 16

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.

View Answer

Question 17

Main pollutants released from iron & steel industry is

A. CO, CO2 & SO2.
B. H2S, NO & SO3.
C. CO2, H2S & NO2.
D. SO3, NO2 & CO2.

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Question 18

Maximum allowable concentration of CO2 in air for safe working is __________ ppm (parts per million).

A. 50
B. 1000
C. 2000
D. 5000

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Question 19

Most of the atmospheric air pollutants are present in large quantity in

A. stratosphere
B. thermosphere
C. trophosphere
D. mesosphere

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Question 20

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

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Question 21

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

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Question 22

Particulates (< 1μm size) remaining suspended in air indefinitely and transported by wind currents are called

A. fumes
B. mists
C. smoke
D. aerosols

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Question 23

Persons working in cement plants and limestone quarries are more prone to disease like

A. cancer
B. asthma
C. silicosis
D. flourosis (bone disease)

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Question 24

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

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Question 25

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.

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Question 26

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.

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Question 27

'Pneumoconiosis' is a disease caused by the inhalation of __________ dust.

A. coal
B. uranium ore
C. iron ore
D. lime

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Question 28

Polluted water having low BOD are most economically treated in

A. sedimentation tanks
B. oxidation ponds
C. sludge digester
D. clarifier

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Question 29

Presence of excess flourine in water causes

A. dental cavity
B. tooth decay
C. fluorosis
D. respiratory disease

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Question 30

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).

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Question 31

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.

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Question 32

Siderosis is a disease caused by the inhalation of __________ dust.

A. coal
B. silica
C. iron
D. none of these

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Question 33

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).

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Question 34

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.

View Answer

Question 35

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

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Question 36

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.

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Question 37

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.

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Question 38

The widest explosive limit is of __________ , thereby making it the most explosive gas.

A. acetylene
B. petrol vapor
C. hydrogen
D. carbon monoxide

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Question 39

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

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Question 40

TLV of mercury in potable (drinking) water is about __________ ppm.

A. 0.001
B. 0.1
C. 1
D. 5

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Question 41

TLV of ozone (O3) and phosgene (COCl2) in air is __________ ppm.

A. 0.1
B. 25
C. 100
D. 1000

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Question 42

Tolerable limit of nitrogen oxides in air is __________ ppm.

A. 0.1
B. 1
C. 5
D. 25

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Question 43

Tri-sodium phosphate is used in boiler water treatment to reduce

A. turbidity
B. caustic embrittlement
C. suspended silica
D. dissolved oxygen

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Question 44

Turbidity of water is an indication of the presence of

A. suspended inorganic matter
B. dissolved solids
C. floating solids
D. dissolved gases

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Question 45

Which is a secondary air pollutant ?

A. Photochemical smog
B. Sulphur dioxide
C. Nitrogen dioxide
D. Dust particles

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Question 46

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

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Question 47

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

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Question 48

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

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Question 49

Which of the following is the most detrimental for water used in high pressure boiler ?

A. Silica
B. Turbidity
C. Phenol
D. Dissolved oxygen

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Question 50

Which of the following pollutants is not emitted during volcanic eruptions ?

A. SO2
B. H2S
D. hydrocarbons

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Question 51

_________ is a raw material sent to and processed in a waste recycling plant.

A. Recyclant
B. Nodules
C. Particulars
D. Recyclate

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Question 52

_________ is the simplest equipment used for collection of solid particulates.

A. Inertial separators
B. Filters
C. Settling chamber
D. Cyclones

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Question 53

Failures within hydrosphere in oxygen cycle can result in the development of:

A. Hyperoxic zones
B. Hypoxic zones
C. Hydrolic zones
D. Hydroxic zones

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Question 54

Hydrogen Peroxide is generated from:

A. Photochemical smog products
B. Explosive manufacturing industry
C. Automobile exhausts
D. Thermal power plants

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Question 55

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

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Question 56

Pollution cases can be classified into _________ types.

A. 4
B. 2
C. 5
D. 6

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Question 57

The living environment, the biosphere consists of __________ components.

A. 2
B. 4
C. 1
D. 3

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Question 58

The presence of gas in water is indicated by:

A. Fizzing sound
B. Foam
C. Bubbles
D. Colour change

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Question 59

To test turbidity of polluted water in the field, _________ is used.

A. Baylis Turbidimeter
B. Jackson Turbidimeter
C. Turbidity tube
D. Turbidity rod

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Question 60

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

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Question 61

When some chemical is mixed with water, _________ is formed.

A. Solution
B. Floc
C. Bubbles
D. Foam

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Question 62

Which of the below leads to disturbance of nitrogen fixation in the soil?

A. Urban waste
B. Fertilizers
C. Pesticides
D. Industrial effluents

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Question 63

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

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Question 64

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

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Question 65

The suitable method for disinfection of swimming pool water is

A. Ultra violet rays treatment
B. Lime treatment
C. By using potassium permanganate
D. Chlorination

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Question 66

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

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Question 67

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

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Question 68

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)

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Question 69

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

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Question 70

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

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Question 71

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

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Question 72

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

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Question 73

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

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Question 74

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

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Question 75

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

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Question 76

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

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Question 77

Sewerage system is designed for

A. Maximum flow only
B. Minimum flow only
C. Average flow only
D. Maximum and minimum flow

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Question 78

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

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Question 79

The ratio of 5 day BOD to ultimate BOD is about

A. 1-3
B. 2-3
C. 3-4
D. 1

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Question 80

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

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Question 81

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

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Question 82

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

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Question 83

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

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Question 84

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

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Question 85

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

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Question 86

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

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Question 87

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

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Question 88

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

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Question 89

The chemical most commonly used to increase speed of sedimentation of sewage is

A. Sulphuric acid
B. Copper sulphate
C. Lime
D. Sodium permanganate

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Question 90

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

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Question 91

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

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Question 92

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

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Question 93

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

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Question 94

Settling velocity increases with

A. Specific gravity of solid particles
B. Size of particles
C. Depth of tank
D. Temperature of liquid

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Question 95

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

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Question 96

Turbidity is measured on

A. Standard silica scale
B. Standard cobalt scale
C. Standard platinum scale
D. Platinum cobalt scale

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Question 97

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

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Question 98

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

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Question 99

When there is no recirculation of sewage, then recirculation factor is

A. 0
B. 1
C. Infinity
D. None of the above

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Question 100

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

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Question 101

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

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Question 102

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

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Question 103

Ground water is usually free from

A. Suspended impurities
B. Dissolved impurities
C. Both suspended and dissolved impurities
D. None of the above

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Question 104

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

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Question 105

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

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Question 106

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

View Answer

Question 107

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

View Answer

Question 108

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

View Answer

Question 109

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

View Answer

Question 110

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

View Answer

Question 111

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

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Question 112

Corrosion in concrete sewers is caused by

A. Septic conditions
B. Dissolved oxygen
C. Chlorine
D. Nitrogen

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Question 113

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

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Question 114

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

View Answer

Question 115

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

View Answer

Question 116

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

View Answer

Question 117

Which of the following values of pH represents a stronger acid?

A. 2
B. 5
C. 7
D. 10

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Question 118

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

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Question 119

Sewage treatment units are designed for

A. Maximum flow only
B. Minimum flow only
C. Average flow only
D. Maximum and minimum flow

View Answer

Question 120

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

View Answer

Question 121

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

View Answer

Question 122

The pathogens can be killed by

A. Nitrification
B. Chlorination
C. Oxidation
D. None of the above

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Question 123

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

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Question 124

Orthotolidine test is used for determination of

A. Dissolved oxygen
B. Residual chlorine
C. Biochemical oxygen demand
D. Dose of coagulant

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Question 125

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

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Question 126

Which of the following compounds is widely used for algae control?

A. Sodium sulphate
B. Copper sulphate
C. Sodium chloride
D. Calcium chloride

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Question 127

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

View Answer

Question 128

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

View Answer

Question 129

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

View Answer

Question 130

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

View Answer

Question 131

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

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Question 132

The devices which are installed for drawing water from the sources are called

A. Aquifers
B. Aquiclude
C. Filters
D. Intakes

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Question 133

Residual chlorine in water is determined by

A. Starch iodide method
B. Orthotolidine method
C. Both (A) and (B)
D. None of the above

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Question 134

The means of access for inspection and cleaning of sewer line is known as

A. Inlet
B. Manhole
C. Drop manhole
D. Catch basin

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Question 135

The treatment of water with bleaching powder is known as

A. Pre-chlorination
B. Super chlorination
C. De-chlorination
D. Hypo-chlorination

View Answer

Question 136

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

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Question 137

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

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Question 138

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

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Question 139

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

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Question 140

The characteristics of fresh and septic sewage respectively are

A. Acidic and alkaline
B. Alkaline and acidic
C. Both acidic
D. Both alkaline

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Question 141

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)

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Question 142

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

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Question 143

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

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Question 144

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

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Question 145

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

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Question 146

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

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Question 147

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

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Question 148

The hourly variation factor is usually taken as

A. 1.5
B. 1.8
C. 2
D. 2.7

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Question 149

Disinfection of water results in

A. Removal of turbidity
B. Removal of hardness
C. Killing of disease bacteria
D. Complete sterilisation

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Question 150

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

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Question 151

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

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Question 152

Composting and lagooning are the methods of

A. Sludge digestion
B. Sludge disposal
C. Sedimentation
D. Filtration

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Question 153

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

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Question 154

The correct relation between theoretical oxygen demand (TOD), Biochemical oxygen demand (BOD) and Chemical oxygen demand (COD) is given by


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Question 155

As compared to shallow wells, deep wells have

A. More depth
B. Less depth
C. More discharge
D. Less discharge

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Question 156

Most of the bacteria in sewage are

A. Parasitic
B. Saprophytic
C. Pathogenic
D. Anaerobic

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Question 157

As compared to cast iron pipes, steel pipes are

A. Heavier
B. Stronger
C. Costlier
D. Less susceptible to corrosion

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Question 158

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

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Question 159

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)

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Question 160

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

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Question 161

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

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Question 162

The gas from sludge digestion tank is mainly composed of

A. Nitrogen
B. Carbon dioxide
C. Hydrogen sulphide
D. Methane

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Question 163

Which of the following unit works in anaerobic conditions?

A. Sludge digestion tank
B. Sedimentation tank
C. Activated sludge treatment
D. Trickling filters

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Question 164

The maximum efficiency of BOD removal is achieved in

A. Oxidation pond
B. Oxidation ditch
C. Aerated lagoons
D. Trickling filters

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Question 165

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

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Question 166

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

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Question 167

The biochemical treatment of sewage effluents is essentially a process of

A. Oxidation
B. Dehydration
C. Reduction
D. Alkalinization

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Question 168

Sewerage system is usually designed for

A. 10 years
B. 25 years
C. 50 years
D. 75 years

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Question 169

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

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Question 170

Sewage treatment units are normally designed for

A. 5 - 10 years
B. 15 - 20 years
C. 30 - 40 years
D. 40 - 50 years

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Question 171

Generally the detention period for grit chambers is kept as

A. 1 minute
B. 5 minutes
C. 24 hours
D. 12 hours

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Question 172

The detention period for oxidation ponds is usually kept as

A. 48 hours
B. 24 hours
C. 10 to 15 days
D. 3 months

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Question 173

Activated carbon is used for

A. Disinfection
B. Removing hardness
C. Removing odours
D. Removing corrosiveness

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Question 174

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

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Question 175

If the sewage contains grease and fatty oils, these are removed in

A. Grit chambers
B. Detritus tanks
C. Skimming tanks
D. Sedimentation tanks

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Question 176

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

View Answer

Question 177

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

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Question 178

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

View Answer

Question 179

Which of the following retards the self purification of stream?

A. Higher temperature
B. Sunlight
C. Satisfying oxygen demand
D. None of the above

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Question 180

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

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Question 181

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)

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Question 182

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)

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Question 183

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

View Answer

Question 184

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)

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Question 185

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

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Question 186

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

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Question 187

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

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Question 188

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

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Question 189

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

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Question 190

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

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Question 191

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

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Question 192

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)

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Question 193

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

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Question 194

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

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Question 195

Which of the following is not a water borne disease?

A. Dysentery
B. Cholera
C. Typhoid
D. Malaria

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Question 196

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

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Question 197

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

View Answer

Question 198

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

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Question 199

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)

View Answer

Question 200

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

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Question 201

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

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Question 202

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

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Question 203

Dissolved oxygen in streams is

A. Maximum at noon
B. Minimum at noon
C. Maximum at midnight
D. Same throughout the day

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Question 204

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

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Question 205

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

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Question 206

The most common cause of acidity in water is

A. Carbon dioxide
B. Oxygen
C. Hydrogen
D. Nitrogen

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Question 207

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

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Question 208

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)

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Question 209

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

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