Environmental Engineering

Question 1

Suspended solid present in the waste water generated in blast furnace gas cooling and cleaning plant is removed by
biological oxygen pond.
radial settling tank (thickener) using coagulant (lime & ferrous sulphate).
lagoons.
filtration.

Answer 1

radial settling tank (thickener) using coagulant (lime & ferrous sulphate).

Question 2

Persons working in cement plants and limestone quarries are more prone to disease like:
cancer
asthma
silicosis
flourosis (bone disease)

Answer 2

silicosis

Question 3

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

Answer 3

aerosols

Question 4

Operating principle of cyclone separator is based on the action of __________ dust particles.
diffusion of
centrifugal force on
gravitational force on
electrostatic force on

Answer 4

centrifugal force on

Question 5

Exposure to small amount of __________ results in high blood pressure & heart disease in human beings.
hydrogen sulphide
mercury
cadmium
asbestos

Answer 5

cadmium

Question 6

Maximum allowable concentration of CO2 in air for safe working is __________ ppm (parts per million).
50
1000
2000
5000

Answer 6

5000

Question 7

Tolerable limit of nitrogen oxides in air is __________ ppm.
0.1
1
5
25

Answer 7

5

Question 8

Iron & manganese present as pollutant in water can not be removed by _____.
ion exchange process.
oxidation followed by settling & filtration.
lime soda process or manganese zeolite process.
chlorination.

Answer 8

chlorination

Question 9

In water chemical treatment plant, use of chloramines ensures _____.
disinfection.
taste & odour control.
weed control in reservoirs.
removal of permanent hardness.

Answer 9

disinfection

Question 10

Which of the following is the common pollutant emitted from metallurgical smelters, thermal power plant and cement plants ?
NOx
Hg
SO2
F

Answer 10

SO2

Question 11

During which of the following operating conditions of an automobile, carbon monoxide content in the exhaust gas is maximum ?
Idle running
Acceleration
Cruising
Deaccelaration

Answer 11

Idle running

Question 12

H2S present in gaseous stream can be removed by adsorption on
silica gel
active carbon
bog iron
limestone powder

Answer 12

bog iron

Question 13

Inhalation of lead compounds present in automobile exhaust (using leaded petrol) causes
blood poisoning.
anaemia.
nervous system disorder.
all (a), (b) & (c).

Answer 13

all (a), (b) & (c).

Question 14

Replenishment of dissolved oxygen in water stream polluted with industrial waste occurs by
natural aeration of water stream.
photosynthetic action of algae.
both (a) & (b).
neither (a) nor (b).

Answer 14

both (a) & (b).

Question 15

Aerodynamic noise resulting from turbulent gas flow is the most prevalent source of valve noise in fluid ilow control. It is caused due to
Reynold stresses
shear forces
both (a) & (b)
neither (a) nor (b)

Answer 15

both (a) & (b)

Question 16

Smoke is produced due to
insufficient supply of combustion air and insufficient time for combustion.
poor quality of fuel and improper mixing of fuel & combustion air.
poor design & overloading of furnace.
all (a), (b) and (c).

Answer 16

all (a), (b) and (c).

Question 17

Fluorosis (a bone disease) is caused by the presence of high concentration of __________ in atmospheric air.
hydrocarbons
hydrogen flouride
hydrogen sulphides
nitrogen dioxide

Answer 17

hydrogen flouride

Question 18

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.
5
500
1000
2000

Answer 18

5

Question 19

Main pollutants released from iron & steel industry is
CO, CO2 & SO2.
H2S, NO & SO3.
CO2, H2S & NO2.
SO3, NO2 & CO2.

Answer 19

CO, CO2 & SO2.

Question 20

Exposure to chemicals having carcinogenic properties cause
dermatitis (skin disorder)
cancer
asphyxiation (suffocation)
asthma

Answer 20

cancer

Question 21

Scale formation in boiler is controlled by
preheating of feed water.
reduction in hardness, silica & alumina in feed water.
keeping the pH value of feed water just below 7.
eliminating H2S in feed water.

Answer 21

reduction in hardness, silica & alumina in feed water.

Question 22

Noise level heard at a distance of about 100 metres from a jet engine with after burner is about __________ decibels.
120
140
170
200

Answer 22

170

Question 23

TLV of mercury in potable (drinking) water is about __________ ppm.
0.001
0.1
1
5

Answer 23

0.001

Question 24

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)?
Lagooning
Activated carbon adsorption
Biological oxidation pond
Chemical coagulation

Answer 24

Activated carbon adsorption

Question 25

Which is a secondary air pollutant ? Photochemical smog Sulphur dioxide Nitrogen dioxide Dust particles

Answer 25

Photochemical smog

Question 26

Which of the following is the most detrimental for water used in high pressure boiler ? Silica Turbidity Phenol Dissolved oxygen

Answer 26

Silica

Question 27

Turbidity of water is an indication of the presence of suspended inorganic matter dissolved solids floating solids dissolved gases

Answer 27

suspended inorganic matter

Question 28

Presence of excess flourine in water causes dental cavity tooth decay fluorosis respiratory disease

Answer 28

fluorosis

Question 29

Siderosis is a disease caused by the inhalation of __________ dust. coal silica iron none of these

Answer 29

iron

Question 30

Which of the following pollutants is not emitted during volcanic eruptions ? SO2 H2S CO hydrocarbons

Answer 30

hydrocarbons

Question 31

The main pollutant in waste water discharged from a petroleum refinery is oil (both in free and emulsified form). Free oil is removed by biological oxygen pond. aerated lagoons. trickling filters. gravity separator having oil skimming devices.

Answer 31

gravity separator having oil skimming devices.

Question 32

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 chlorination treating in biological oxygen pond chemical coagulation none of these

Answer 32

treating in biological oxygen pond

Question 33

Which of the following dust collection equipments is the least efficient (for sub-micronic particles) ? Dust catcher (gravity type) Cyclone separator Bag filter Hollow wet scrubber

Answer 33

Dust catcher (gravity type)

Question 34

Dust collection efficiency of a cyclone separator depends upon its diameter. inlet gas velocity. overall height. all (a), (b) & (c).

Answer 34

all (a), (b) & (c).

Question 35

Ionisation potential employed in the industrial electrostatic precipitator is of the order of 30 to 70 kV DC 30 to 70 kV AC 230 V AC 230 V DC

Answer 35

30 to 70 kV DC

Question 36

The widest explosive limit is of __________ , thereby making it the most explosive gas. acetylene petrol vapor hydrogen carbon monoxide

Answer 36

acetylene

Question 37

Aerobic biological oxidation ponds used for the purification of polluted water destroys/removes pathogen from the sewage. is not very effective for nonbiodegradable substances (e.g. ABS) containing effluents. destroys/removes pathogen much more effectively if the sewage is chlorinated. all (a), (b) & (c).

Answer 37

all (a), (b) & (c).

Question 38

Polluted water having low BOD are most economically treated in sedimentation tanks oxidation ponds sludge digester clarifier

Answer 38

oxidation ponds

Question 39

Tri-sodium phosphate is used in boiler water treatment to reduce turbidity caustic embrittlement suspended silica dissolved oxygen

Answer 39

caustic embrittlement

Question 40

The commonest form of iron & manganese found in ground water as pollutant is in the form of their carbonates bi-carbonates chlorides sulphides

Answer 40

bi-carbonates

Question 41

80% less than 200 mesh size particles are called smoke powder grit aggregates

Answer 41

powder

Question 42

Coal washing waste water containing about 3% suspended solids (comprising of clay, slate, stone etc.) is treated for solid particles removal by chemical coagulation. in sedimentation tanks equipped with mechanical scrapper. in vacuum filter. in clarifiers.

Answer 42

in sedimentation tanks equipped with mechanical scrapper.

Question 43

Inhalation of lead compounds present in the automobile exhausts (using leaded petrol) causes blood poisoning. anaemia. nervous system disorder. all (a), (b) and (c).

Answer 43

all (a), (b) and (c).

Question 44

TLV of ozone (O3) and phosgene (COCl2) in air is __________ ppm. 0.1 25 100 1000

Answer 44

0.1

Question 45

Most of the atmospheric air pollutants are present in large quantity in stratosphere thermosphere trophosphere mesosphere

Answer 45

trophosphere

Question 46

Pick out the wrong statement. Caustic embrittlement of boiler's metallic parts is caused by high concentration of caustic soda in boiler feed water. Cooling and freezing of water kills the bacteria present in it. With increasing boiler operating pressure of steam, the maximum allowable concentration of silica in feed water goes on decreasing. Dissolved oxygen content in high pressure boiler feed water should be nil.

Answer 46

Cooling and freezing of water kills the bacteria present in it. Many bacteria survive freezing temps.

Question 47

'Pneumoconiosis' is a disease caused by the inhalation of __________ dust. coal uranium ore iron ore lime

Answer 47

coal

Question 48

The ratio of oxygen available to the oxygen required for stabilisation of sewage is called the bacterial stability factor. relative stability. biological oxygen demand (BOD). oxygen ion concentration.

Answer 48

relative stability.

Question 49

Pick out the wrong statement. The concentric atmosphere layer just above troposphere is called stratosphere, which is rich in ozone. Mesosphere is characterised by very low atmospheric pressure and low temperature. Troposhere is a dusty zone containing water vapor and clouds. The radio waves used in the long distance radio communication are reflected back to earth by stratosphere.

Answer 49

The radio waves used in the long distance radio communication are reflected back to earth by stratosphere. They are reflected back in the ionosphere.

Question 50

Most efficient and suitable dust removal equipment for removal of flyash from flue gas in a thermal power plant is the gravity settling chamber cyclone separator electrostatic precipitator bag filter

Answer 50

electrostatic precipitator

Question 51

Which of the following is not a secondary air pollutant ? Ozone Photochemical smog Sulphur dioxide All (a), (b) & (c)

Answer 51

Sulphur dioxide Ozone and photochemical smog are formed from NOx and VOCs.

Question 52

The concentration of water vapour in troposphere, which depends upon the altitude & temperature varies in the range of zero to __________ percent. 1 4 8 12

Answer 52

4

Question 53

The main industrial source of emission of hydrogen sulphide air pollutant is petroleum refineries. coal based thermal power plants. pulp and paper plant. metallurgical roasting & smelting plant.

Answer 53

coal based thermal power plants.

Question 54

Waste/polluted water discharged from electroplating, blast furnace and coal mining industries contain mainly __________ substances. radioactive organic inorganic none of these

Answer 54

inorganic

Question 55

Sound produced by an automobile horn heard at a distance of 1.5 metres corresponds to about __________ decibels. 90 120 150 180

Answer 55

120

Question 56

Moist atmospheric air at high temperature (e.g., in summer) having high concentration of sulphur dioxide causes fading of dyes on textiles. corrosion, tarnishing & soiling of metals. reduced strength of textiles. all (a), (b) and (c).

Answer 56

all (a), (b) and (c).

Question 57

Nitrogen oxides (NOx) is not produced in the __________ industry. nitric acid making nitrogenous fertiliser detergent any of these

Answer 57

detergent

Question 58

World's worst radioactive pollution was caused by nuclear reactor disaster which occured in Arizona (U.S.A.) Chernobyl (undivided U.S.S.R.) Pensylvania (U.S.A.) Moscow (U.S.S.R.)

Answer 58

Chernobyl (undivided U.S.S.R.)

Question 59

Dissolved oxygen content in river water is around __________ ppm. 5 100 250 500

Answer 59

5

Question 60

Oil and grease present in an emulsified state in waste water discharged from industries can be removed by biological oxidation. skimming off. settling out using chemical reagents. chlorination.

Answer 60

settling out using chemical reagents.

Question 61

The amount of chemical coagulant added for treatment of polluted water __________ with increase in temperature of the polluted water to be treated. decreases. increases. remains constant. may increase or decrease ; depends on the chemical characteristics of polluted water.

Answer 61

decreases.

Question 62

Particles having diameter greater than 75 μm (micrometer = 10-6 mm) are called grit dust powder smoke

Answer 62

grit

Question 63

Which of the following is the most severe air pollutant ? hydrocarbons NOx SO2 CO

Answer 63

NOx

Question 64

Presence of bacteria in potable (drinking) water causes turbidity disease bad odour bad taste & colour

Answer 64

disease

Question 65

What are the methods of treatment & disposal of radioactive wastes ? Evaporation & chemical precipitation. Biological methods & adsorption in ion exchange materials. Fixing into a solid mass with cement and sinking deep in the sea. All (a), (b) & (c).

Answer 65

All (a), (b) & (c).

Question 66

Bacterial aerobic oxidation of polluted water in biological oxidation ponds is done to purify it. Presence of bacteria helps in coagulation and flocculation of colloids. oxidation of carbonaceous matter to CO2. nitrification or oxidation of ammonia derived from breakdown of nitrogeneous organic matter to the nitrite and eventually to the nitrate. all (a), (b) and (c).

Answer 66

all (a), (b) and (c).

Question 67

Main pollutant present in automobile exhaust is CO CO2 NO hydrocarbons

Answer 67

CO

Question 68

Maximum allowable noise exposure limits for a man working for 8 hours a day in a noisy chemical plant is about __________ decibels. 20 60 90 120

Answer 68

90

Question 69

Industrial workers working in leather tanning & manufacturing units are prone to suffer from respirtory ailments (e.g. bronchitis). skin diseases (e.g. dermatities). silicosis. blurred vision.

Answer 69

skin diseases (e.g. dermatities).

Question 70

Pick out the wrong statement. Biological oxygen demand (B.O.D.) value of a sewerage sample is always lower than its chemical oxygen demand (C.O.D.) value. Environmental pollution by NOx emission is much higher by four stroke petrol engines as compared to the two stroke engines. Temperature in stratosphere rises with increasing altitude. The characteristic of a green house body is that it allows the long wavelength incoming solar radiation to come in but does not allow the short wavelength infra red radiation to escape out of the earth's atmosphere.

Answer 70

The characteristic of a green house body is that it allows the long wavelength incoming solar radiation to come in but does not allow the short wavelength infra red radiation to escape out of the earth's atmosphere. Greenhouse gases can absorb and emit radiation of all wavelengths.

Question 71

Peroxyacyl nitrate (PAN), a pollutant is found in the automobile exhaust. flue gas of coal based power plant. exhaust of nitric acid plant. exhaust of sulphuric acid plant.

Answer 71

automobile exhaust.

Question 72

Foaming and priming in boiler operation can be reduced by reduction in __________ in feed water. turbidity color (Hazen) total solids all (a), (b) & (c)

Answer 72

all (a), (b) & (c)

Question 73

Ambient noise level can be reduced by __________ decibels by planting trees (like coconut, neem etc.) near public utility buildings (like hospitals & schools). 1-2 5-10 15-20 25-30

Answer 73

5-10

Question 74

Pick out the wrong statement. Catalytic converter is fitted in automobiles to reduce carbon monoxide concentration in exhaust emissions. Inhalation of pollutant carbon monoxide results in death by asphyxiation. Sulphur dioxide is the main pollutant emitted from the exhaust of petrol driven automobiles. Decomposition of plants containing chlorophyll is a natural source of carbon monoxide in atmosphere.

Answer 74

Sulphur dioxide is the main pollutant emitted from the exhaust of petrol driven automobiles.

Question 75

Which of the following radioactive wastes emits all α, β & γ rays and hence is the most hazardous of all radioactive emitters? I-131 Sr-90 Au-198 Ra-226

Answer 75

Ra-226

Question 76

COD of raw municipal sewage may be in the range of about __________ mg/litre. 1-2 5-10 90-120 1500-2500

Answer 76

90-120

Question 77

Maximum permissible turbidity in potable water is __________ ppm. 1 10 250 1000

Answer 77

10

Question 78

Presence of __________ hardness is responsible for the temporary hardness in water. carbonate calcium choride sulphate

Answer 78

calcium

Question 79

Dose of chlorine for disinfection of water is about __________ mg/litre of water. 0.01 0.1 0.3 1

Answer 79

1

Question 80

A shallow pond in which the sewage is retained and biologically treated is called oxidation Imhoff tank lagoon skimming tank

Answer 80

oxidation

Question 81

Which is the most practical and economical method for removal of suspended solid matter from polluted water ? Sedimentation Skimming off Chlorination Biological oxidation

Answer 81

Sedimentation

Question 82

Atmospheric pollution caused by the exhaust gas of supresonic transport air-crafts is mostly in the atmospheric region called thermosphere stratosphere troposphere mesosphere

Answer 82

stratosphere

Question 83

Iron & manganese present in the polluted water is removed by simple filtration. oxidation followed by settling & filtration. chemical coagulation. chlorination only.

Answer 83

oxidation followed by settling & filtration.

Question 84

Water effluent generated in printing industry is decolourised by ion exchange technique. reverse osmosis. electrolytic decomposition. adsorption.

Answer 84

electrolytic decomposition.

Question 85

Thermal pollution of water increases its toxicity and oxidation of oxygen demanding waste besides favouring bacterial growth. A rise in water temperature by 10°C, doubles the toxic effects of __________ present in it. coal ash potassium cyanide ortho-xylene none of these

Answer 85

potassium cyanide

Question 86

_________ can not control the noise pollution. Use of silencers Green house gases Vibration damping Tree plantation

Answer 86

Green house gases

Question 87

Ozone level is generally found to be depleted in India in the month of February July April December

Answer 87

December

Question 88

Noise level during normal conversation among men is about __________ decibles. 10 45 90 115

Answer 88

45

Question 89

'Particulate' air pollutants are finely divided solids and liquids. Which of the following is not a 'particulate' ? Dust & mists Smoke & fumes Photochemical smog & soot None of these

Answer 89

None of these

Question 90

Foul odour and bad taste of water is removed by treating with alum bleaching powder activated carbon copper sulphate.

Answer 90

activated carbon

Question 91

Presence of __________ in water stream are deleterious to aquatic life. soluble and toxic organics. suspended solids. heavy metals and cynides. all (a), (b) & (c).

Answer 91

all (a), (b) & (c).

Question 92

Acute danger to human life (i.e. death) exists, if the concentration of CO2 in atmospheric air exceeds __________ percent (by volume). 1 3 7 20

Answer 92

20

Question 93

Methyl iso-cynate (MIC) gas (TLV <1 ppm), which caused Bhopal gas tragedy in 1984 falls under the category of __________ toxic gas. moderately highly extremely very extremely

Answer 93

very extremely

Question 94

Noise level heard inside a bus in busy city traffic or inside a sub-way train corresponds to about __________ decibels. 75 95 120 140

Answer 94

95

Question 95

Presence of volatile compounds like gasoline, oil, alcohol, ether etc. in municipal sewers may cause explosion non biodegradable foam undesirable plant growth corrosion

Answer 95

explosion

Question 96

Noise produced by cooling fans (employed in air cooled heat exchangers or cooling tower) is mainly caused due to the turbulence created by blade passage through air. It can be reduced by use of a slower fan with greater number of blades. of increased diameter. both (a) & (b). neither (a) nor (b).

Answer 96

both (a) & (b).

Question 97

Presence of soluble organics in polluted water causes undesirable plants growth. depletion of oxygen. fire hazards. explosion hazards.

Answer 97

depletion of oxygen.

Question 98

Which of the following pollutants, if present in atmosphere is detectable by its odour ? CO SO2 NO2 CO2

Answer 98

SO2