Envi (Indiabix) Flashcards by Nuñez Ronnie

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.

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

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Persons working in cement plants and limestone quarries are more prone to disease like
a. Cancer
b. Asthma
c. Silicosis
d. flourosis (bone disease)

c. Silicosis

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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

b. centrifugal force on

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Particulates (< 1μm size) remaining suspended in air indefinitely and transported by wind currents are called
a. Fumes
b. Mists
c. Smoke
d. Aerosols

c. Smoke

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Exposure to small amount of __________ results in high blood pressure & heart disease in human beings.
a. hydrogen sulphide
b. mercury
c. Cadmium
d. asbestos

c. Cadmium

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

d. 5000

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Tolerable limit of nitrogen oxides in air is __________ ppm.
a. 0.1
b. 1
c. 5
d. 25

c. 5

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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.

d. chlorination.

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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.

a. Disinfection.

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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

c. SO2

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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

a. Idle running

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H2S present in gaseous stream can be removed by adsorption on
a. silica gel
b. active carbon
c. bog iron
d. limestone powder

c. bog iron

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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).

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

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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).

c. both (a) & (b).

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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)

c. both (a) & (b)

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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).

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

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Fluorosis (a bone disease) is caused by the presence of high concentration of __________ in atmospheric air.
a. Hydrocarbons
b. hydrogen fluoride
c. hydrogen sulphides
d. nitrogen dioxide

b. hydrogen fluoride

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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

a. 5

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

a. CO, CO2 & SO2.

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Exposure to chemicals having carcinogenic properties cause
a. dermatitis (skin disorder)
b. cancer
c. asphyxiation (suffocation)
d. asthma

b. cancer

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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.

b. reduction in hardness, silica & alumina in feed water.

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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

c. 170

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

a. 0.001

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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

b. Activated carbon

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Which is a secondary air pollutant ? a. Photochemical smog b. Sulphur dioxide c. Nitrogen dioxide d. Dust particles

a. Photochemical smog

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

a. Silica

Turbidity of water is an indication of the presence of a. suspended inorganic matter b. dissolved solids c. floating solids d. dissolved gases

a. suspended inorganic matter

Presence of excess fluorine in water causes a. dental cavity b. tooth decay c. Fluorosis d. respiratory disease

c. Fluorosis

Siderosis is a disease caused by the inhalation of __________ dust. a. Coal b. Silica c. Iron d. none of these

c. Iron

Which of the following pollutants is not emitted during volcanic eruptions ? a. SO2 b. H2S c. CO d. hydrocarbons

d. hydrocarbons

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.

d. gravity separator having oil skimming devices.

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

b. treating in biological oxygen pond

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

a. Dust catcher (gravity type)

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).

d. both (b) and (c).

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

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

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

a. 30 to 70 kV DC

The widest explosive limit is of __________ , thereby making it the most explosive gas. a. Acetylene b. petrol vapor c. Hydrogen d. carbon monoxide

a. Acetylene

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).

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

Polluted water having low BOD are most economically treated in a. sedimentation tanks b. oxidation ponds c. sludge digester d. clarifier

b. oxidation ponds

Tri-sodium phosphate is used in boiler water treatment to reduce a. Turbidity b. caustic embrittlement c. suspended silica d. dissolved oxygen

b. caustic embrittlement

. 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

b. Bi-carbonates

80% less than 200 mesh size particles are called a. smoke b. Powder c. Grit d. aggregates

b. Powder

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.

b. in sedimentation tanks equipped with mechanical scrapper.

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).

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

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

a. 0.1

Most of the atmospheric air pollutants are present in large quantity in a. Stratosphere b. Thermosphere c. Trophosphere d. mesosphere

c. Trophosphere

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.

b. Cooling and freezing of water kills the bacteria present in it.

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

a. coal

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.

b. relative stability.

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.

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

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

c. electrostatic precipitator

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

c. Sulphur dioxide

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

b. 4

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

b. coal based thermal power plants.

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

c. inorganic

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

b. 120

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

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

Nitrogen oxides (NOx) is not produced in the __________ industry. a. nitric acid making b. nitrogenous fertiliser c. Detergent d. any of these

c. Detergent

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

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

Dissolved oxygen content in river water is around __________ ppm. a. 5 b. 100 c. 250 d. 500

a. 5

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

c. settling out using chemical reagents.

The amount of chemical coagulant added for treatment of polluted water __________ with increase in temperature of the polluted water to be treated. a. Decreases. b. Increases. c. remains constant. d. may increase or decrease ; depends on the chemical characteristics of polluted water.

a. Decreases

Particles having diameter greater than 75 μm (micrometer = 10-6 mm) are called a. Grit b. Dust d. Powder c. smoke

a. Grit

Which of the following is the most severe air pollutant ? a. Hydrocarbons b. NOx c. SO2 d. CO

b. NOx

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

Presence of bacteria in potable (drinking) water causes a. Turbidity b. Disease c. bad odour d. bad taste & colour

b. Disease

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

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

Main pollutant present in automobile exhaust is a. CO b. CO2 c. NO d. hydrocarbons

a. CO

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

c. 90

Industrial workers working in leather tanning & manufacturing units are prone to suffer from a. respiratory ailments (e.g. bronchitis). b. skin diseases (e.g. dermatitis). c. Silicosis. d. blurred vision.

b. skin diseases (e.g. dermatitis).

Pick out the wrong statement. a. Biological oxygen demand (B.O.D.) value of a sewerage sample is always lower than its chemical oxygen demand (C.O.D.) value. b. Environmental pollution by NOx emission is much higher by four stroke petrol engines as compared to the two stroke engines. c. Temperature in stratosphere rises with increasing altitude. d. 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.

d. 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.

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

a. automobile exhaust.

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

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

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

b. 5-10

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

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

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

c. 90-120

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

d. Ra-226

Maximum permissible turbidity in potable water is __________ ppm. a. 1 b. 10 c. 250 d. 1000

b. 10

Presence of __________ hardness is responsible for the temporary hardness in water. a. Carbonate b. Calcium c. Choride d. sulphate

b. Calcium

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

d. 1

A shallow pond in which the sewage is retained and biologically treated is called a. Oxidation b. Imhoff tank c. Lagoon d. skimming tank

a. Oxidation

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

a. Sedimentation

Atmospheric pollution caused by the exhaust gas of supersonic transport air-crafts is mostly in the atmospheric region called a. Thermosphere b. Stratosphere c. Troposphere d. mesosphere

c. Troposphere

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

b. oxidation followed by settling & filtration.

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

c. electrolytic decomposition.

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. a. coal ash b. potassium cyanide c. Ortho-xylene d. none of these

b. potassium cyanide

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

b. Green house gases

Ozone level is generally found to be depleted in India in the month of a. February b. July c. April d. December

d. December

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

b. 45

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

d. None of these

Foul odour and bad taste of water is removed by treating with a. Alum b. bleaching powder c. activated carbon d. copper sulphate.

c. activated carbon

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

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

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

d. 20

Methyl iso-cynate (MIC) gas (TLV <1 ppm), which caused Bhopal gas tragedy in 1984 falls under the category of __________ toxic gas. a. Moderately b. Highly c. Extremely d. very extremely

d. very extremely

Noise level heard inside a bus in busy city traffic or inside a subway train corresponds to about __________ decibels. a. 75 b. 95 c. 120 d. 140

b. 95

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

a. Explosion

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 a. with greater number of blades. b. of increased diameter. c. both (a) & (b). d. neither (a) nor (b).

c. both (a) & (b).

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

b. depletion of oxygen.

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

b. SO2

Exposure to chemicals having carcinogenic properties cause a. dermatitis (skin disorder) b. cancer c. Asphyxiation d. asthma

b. cancer

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