Category: Environmental Engineering Objective Questions

Environmental Engineering Multiple Choice Questions on “Methods of Disinfection”.

1. Which water treatment process is done after filtration of water?
a) Primary sedimentation
b) Disinfection
c) Secondary sedimentation
d) Flocculation
Answer: b
Clarification: Disinfection is a process which is done to kill microorganism present in the water after the filtration process.

2. Which of the following is wrong regarding disinfection?
a) It should be readily available at reasonable cost
b) Its method of application should be simple
c) It should render the water toxic for its intended use
d) It should act as safeguard against re-contamination
Answer: c
Clarification: Disinfection should not render the water toxic, objectionable and unpalatable for its intended use.

3. Boiling of water is a _____ method of disinfection.
a) Physical
b) Chemical
c) Mechanical
d) Electrical
Answer: a
Clarification: Boiling of water is a physical method of disinfection which is also called as disinfection by heat.

4. Sunlight is a ________ method of disinfection.
a) Physical
b) Chemical
c) Mechanical
d) Electrical
Answer: a
Clarification: Sunlight is a natural disinfection. Irradiation by ultraviolet rays promotes disinfection.

5. Which of the following is a chemical method of disinfection?
a) Disinfection by heat
b) Disinfection by light
c) Metal ions
d) Metal ions, Alkalis and acids
Answer: d
Clarification: Disinfection by heat and light are physical methods of disinfection whereas metal ions, alkalis and acids are chemical methods of disinfection.

6. The pathogenic bacteria do not last long at a pH ______
a) >11
b) <11
c) <8
d) >8
Answer: a
Clarification: The pathogenic get killed at pH>11 which is very alkaline in nature or at pH=3 which is highly acidic.

7. Which minor method of disinfection is effective in complete sterilization of water?
a) Boiling method
b) Excess lime treatment
c) Silver treatment
d) Ultraviolet ray treatment
Answer: a
Clarification: Boiling method is effective in complete sterilization of water as it kills all the bacteria and microorganism present in water.

8. What is the dose of lime required in the excess lime treatment?
a) 10-20ppm
b) 0-10ppm
c) 5-10ppm
d) 5-20ppm
Answer: a
Clarification: The dose of lime used in the excess lime treatment is 10-20ppm and the excess lime can be removed by the process of re-carbonation.

9. At what pH, the E-Coli bacteria will die in the water?
a) 6
b) 7
c) 9
d) >9.5
Answer: d
Clarification: The E-Coli bacteria will die at a pH>9. This can be done with the help of excess lime treatment.

10. The depth of water while using ultra violet ray treatment for disinfection should be ____
a) 35cm
b) 46cm
c) 28cm
d) 10cm
Answer: d
Clarification: The depth of water while using ultra violet ray treatment for disinfection should not exceed 10 cm and its turbidity should be in the range of 15-20ppm.

11. Which method of disinfection is mainly used in rural areas?
a) Boiling method
b) Excess lime treatment
c) Potassium permanganate treatment
d) Silver treatment
Answer: c
Clarification: The Potassium permanganate treatment is used in rural areas where most of the water is drawn from a well which contains the least amount of bacteria.

12. The dose of KMnO₄ required for disinfection of water is _______ ppm.
a) 1-2
b) 2-3
c) 3-4
d) 4-7
Answer: a
Clarification: The normal dose of KMnO₄ required for disinfection of water varies between 1 to 2ppm with a contact period of 4 to 6 hours.

13. Addition of KMnO₄ to water imparts _____ color.
a) Blue
b) Red
c) Pink
d) White
Answer: c
Clarification: Addition of KMnO₄ to water imparts pink color. It not only kills the bacteria, but also helps in oxidizing the taste producing organic matter.

Environmental Engineering Multiple Choice Questions on “Material for Sewers”.

1. The diameter of plain cement concrete pipes used for sewerage system is __________
a) 20mm
b) 30mm
c) 90mm
d) 63mm
Answer: c
Clarification: The range of diameter of plain cement concrete pipes for sewerage system is from 80mm to 450mm and its thickness varies from 25 to 35mm.

2. The grade of concrete used in plain cement concrete sewer is __________
a) M5
b) M10
c) M15
d) M20
Answer: d
Clarification: M20 grade of concrete is used in plain cement concrete sewer. It includes cement, fine aggregate and coarse aggregate in the ratio of 1:1.5:3.

3. Which of the following is incorrect regarding Cement concrete sewers?
a) They are economical
b) Can be manufactured at the site
c) They can be made of any desired strength
d) They cannot withstand tensile stress
Answer: d
Clarification: Cement concrete sewer can withstand internal and external pressure and are strong enough to resist both tensile and compressive stress.

4. The crown corrosion takes place due to formation of __________
a) CO₂
b) H₂O
c) H₂S
d) HCl
Answer: c
Clarification: The crown corrosion takes place due to the formation of H₂S which takes place because of aerobic and anaerobic condition in lower layers of sewage.

5. The cement concrete sewers are lined with vitrified clay lining to prevent __________
a) Dampness of sewer
b) Algae growth in the sewer
c) Crown corrosion
d) Foul smell of sewer
Answer: c
Clarification: The interiors of the sewers are lined with vitrified clay to prevent corrosion and erosion of sewer.

6. Which of the following method is not used for treating crown corrosion?
a) Full runs of sewer
b) Increasing the sulfate content of sewage
c) Aeration and chlorination of sewage
d) Vitrified clay lining of sewer
Answer: b
Clarification: The pretreatment of sewage is done for treating the crown corrosion to reduce the sulfate content from sewage.

7. Which of the following is incorrect regarding Stoneware sewer?
a) They can withstand tensile stress
b) They are highly resistant to sulfide corrosion
c) They have smooth interior
d) They are high compressive strength
Answer: a
Clarification: Stoneware sewer can not be used where sewage flow under pressure as they are weak in tension.

8. The range of diameter of cast iron sewer is __________
a) 20-100mm
b) 150-750mm
c) 40-250mm
d) 100-250mm
Answer: b
Clarification: The diameter of cast iron sewer lies between 150mm and 750mm and its length lies between 3 m to 3.5m.

9. Identify the correct statement from the following regarding Cast iron sewer.
a) They have low internal pressure
b) They are not leakage proof
c) They cannot withstand heavy external loads
d) They are preferred in water supply lines
Answer: d
Clarification: Cast iron is 100% leakage proof, so they are preferred in water supply lines.

Environmental Engineering MCQs on “Grit Chambers, Tanks and Vacuum Floatation”.

1. The unit of dynamic viscosity is ____________
a) Metre²/Sec
b) Metre/Sec
c) Pa * Sec
d) Dimensionless
Answer: c
Clarification: The dynamic viscosity is the ratio of shear stress to velocity gradient. Its unit is Pa * Sec.

2. Which of the following has minimum detention period?
a) Grit chamber
b) Sedimentation tank
c) Oxidation ditch
d) Oxidation pond
Answer: a
Clarification: Grit chamber has a minimum detention period with a value of 40-60 seconds.

3. The relation between dynamic and kinematic viscosity is given by ____________
a) Dynamic viscosity = Kinematic viscosity * Density of water
b) Kinematic viscosity = Dynamic viscosity + Density of water
c) Dynamic viscosity = Kinematic viscosity * Density of water
d) Dynamic viscosity = Kinematic viscosity / Density of water
Answer: c
Clarification: μ = v * ρ, μ = dynamic viscosity, v = kinematic viscosity and ρ = density of water.

4. The dimension formula of dynamic viscosity is ____________
a) ML^-1T
b) ML^-1T^-1
c) ML^-2T^-2
d) ML^-1T^-3
Answer: b
Clarification: The dimension formula of dynamic viscosity is ML^-1T^-1 and it can be measured in kg m^-1 s^-1.

5. The dimension formula of kinematic viscosity is ____________
a) L^-1T
b) ML^-1T^-1
c) ML^-2T^-2
d) L²T^-1
Answer: d
Clarification: The dimension formula of kinematic viscosity = ML^-1T^-1 / ML^-3 = L² T^-1.

6. The coefficient of drag for a transition settling is ____________
a) CD = 18.5/R^0.6
b) CD = 24/R
c) CD = 8.5/R^0.6
d) CD = R/24
Answer: a
Clarification: When Reynolds number ‘R’ lies between 1 and 1000, the coefficient of drag CD is given by CD = 18.5/R^0.6.

7. In which of the following, large impurities are attached with air bubbles to remove it from the wastewater?
a) Sludge digestion tank
b) Primary sedimentation
c) Vacuum floatation
d) Oxidation pond
Answer: c
Clarification: In skimming tanks, large impurities are attached with air bubbles to decrease its density, they float in sewage and are finally removed by skimming troughs.

8. Which of the following has a minimum detention period?
a) Sludge digestion tank
b) Primary sedimentation
c) Skimming tank
d) Oxidation pond
Answer: c
Clarification: The skimming tank has a minimum detention period with a value of 3 minutes.

9. The design velocity of flow of a detritus tank is ____________
a) 1m/Sec
b) 1.2m/Sec
c) 0.9m/Sec
d) 0.5m/Sec
Answer: c
Clarification: The detritus tanks are able to remove grit and sand particles by having a design velocity of 0.9m/Sec.

10. Which of the following device is used for the removal of oil and grease?
a) Skimming tank
b) Grit chambers
c) Tube settlers
d) Flocculator
Answer: a
Clarification: The skimming tank is used after the grit chamber to remove oil and grease from the sewage.

11. The detention period of detritus tank is ____________
a) 40 seconds
b) 1 minute
c) 3 minute
d) 1 hour
Answer: c
Clarification: The detention period of detritus tank is 3 minutes. It is used to remove the grit present in the wastewater.

12. A pressure difference of _____________ is applied to the vacuum floatation method to remove impurities from sewage.
a) 0.5 atm
b) 1 atm
c) 1.5 atm
d) 2 atm
Answer: b
Clarification: In the vacuum floatation method, pressure of 1 atm is applied in sewage followed by the vacuum that creates a pressure difference of 1 atm, resulting in the formation of bubbles that helps in the removal of large impurities in sewage.

To practice MCQs on all areas of Environmental Engineering, .

Environmental Engineering Multiple Choice Questions on “Municipal Solid Waste”.

1. The process of burning of municipal solid waste at high temperature is called ____________
a) Incineration
b) Composting
c) Land filing
d) Shredding
Answer: a
Clarification: Incineration is the most sanitary method of disposal of municipal solid waste. Solid waste should have a high calorific value.

2. Which of the following is a biodegradable waste?
a) Polythene bags
b) Synthetic fiber
c) Food waste
d) Paper
Answer: c
Clarification: Polythene bags, synthetic fiber and paper are non biodegradable wastes whereas food waste is a biodegradable waste.

3. In which method of disposal of municipal solid waste, the waste is dumped in the soil?
a) Incineration
b) Composting
c) Land filing
d) Shredding
Answer: c
Clarification: Land filling is a process of disposal of solid waste under the soil. It is usually done in low lying areas to prevent unhygienic conditions.

4. Which of the following is correct regarding disposal of waste by land filling?
a) Economical method
b) Preferred in low lying areas
c) Foul gases are not produced
d) Separation of different types of waste not required
Answer: c
Clarification: Land fill gases are produced during the dumping of waste. They are foul smell creating unhygienic conditions.

5. The density of ash produced in the municipal solid waste is ___________
a) 100 kg/m³
b) 450 kg/m³
c) 700 kg/m³
d) 1000 kg/m³
Answer: c
Clarification: The range of the d density of ash produced from the municipal solid waste is 700-850kg/m³.

6. The process of decomposition of biodegradable solid waste by earthworms is called ___________
a) Land fills
b) Shredding
c) Vermi-composting
d) Composting
Answer: c
Clarification: The process of decomposition of biodegradable solid waste by earthworms is called Vermi-composting.

7. The waste produced in cotton mills are ___________
a) Municipal solid waste
b) Non biodegradable waste
c) Hazardous waste
d) Non hazardous waste
Answer: d
Clarification: The industrial waste is produced by cotton mills which are biodegradable and are non hazardous.

8. Which of the following is not the land filling method?
a) Bangalore method
b) Area method
c) Depression method
d) Trench method
Answer: a
Clarification: Bangalore method is a method of composting whereas area, depression and trench method are the land filling method.

9. ______ is a liquid that passes through solid waste and extracts suspended impurities from it.
a) Leachate
b) Sludge
c) Distilled water
d) Municipal waste
Answer: a
Clarification: Leachate is a liquid that passes through solid waste and extracts suspended impurities from it. It can be minimized by the use of clay lines.

10. Which of the following is not the municipal solid waste?
a) Radioactive substance
b) Ashes
c) Food waste
d) Rubbish
Answer: a
Clarification: Rubbish, food waste and food waste are municipal solid waste, whereas radioactive substances are industrial waste.

11. Which of the following waste can be decomposed by bacteria?
a) Radioactive substance
b) Ashes
c) Food waste
d) Rubbish
Answer: c
Clarification: Food waste can be decomposed by bacteria as they are biodegradable waste, whereas ashes, rubbish is non biodegradable.

12. ______ is the cutting and tearing of municipal solid waste.
a) Land fills
b) Shredding
c) Pulverization
d) Composting
Answer: b
Clarification: Shredding is the cutting and tearing of municipal solid waste. It helps in reducing the size and volume of municipal solid waste.

13. _________ is the crushing and grinding of municipal solid waste.
a) Land fills
b) Shredding
c) Pulverization
d) Composting
Answer: c
Clarification: Pulverization is the crushing and grinding of municipal solid waste. It changes the character of municipal solid waste and reduced its volume by 40%.

14. In which method of composting, decomposition of anaerobic waste takes place?
a) Indian method
b) Depression method
c) Bangalore method
d) Trench method
Answer: c
Clarification: In the Bangalore method of composting, decomposition of anaerobic waste takes place. It is better than the Indore method.

15. Which of the following is a biological method of disposal of municipal solid waste?
a) Land fills
b) Shredding
c) Pulverization
d) Composting
Answer: d
Clarification: Composting is a biological method of decomposing the municipal solid waste under aerobic and anaerobic condition. It results in the production of humus.

Environmental Science Multiple Choice Questions on “Greenhouse Gases – 2”.

1. The GWP depends on which of the following factors?
a) Absorption capability of IR radiations
b) Atmospheric life-time
c) Range of IR wavelengths it can absorb
d) All of the mentioned
Answer: d
Clarification: The global warming potential of a given gas depends on its absorption capability over range of IR wavelengths and how long it stays in the atmosphere.

2. Which of the following mentioned GHGs has the highest atmospheric lifetime?
a) Carbon tetrafluoride
b) Nitrous oxide
c) Methane
d) CFC
Answer: a
Clarification: Among the mentioned gases, carbon tetrafluoride has the largest life time of 50,000 years and a GWP of approximately 5000 over a period of 20 years.

3. Which of the following gases has the highest radiative efficiency?
a) Sulphur hexafluoride
b) Carbon tetrachloride
c) PFTBA
d) CFC
Answer: c
Clarification: Perfluorotributylamine used as in heat transfer and electrical industry has the highest radiative efficiency, i.e. it can effectively trap the long wave radiation better than other greenhouse gases.

4. Which of the following compounds have the highest GWP?
a) Nitrous oxide
b) CFC
c) Water vapour
d) Sulphur hexafluoride
Answer: d
Clarification: Sulphur hexafluoride has a potential of warming the planet 16,300 times greater than carbon dioxide.

5. Anthropogenic sources of carbon dioxide are 20 times greater than natural carbon dioxide sources.
a) True
b) False
Answer: b
Clarification: Natural sources of CO2 are twenty times greater than anthropogenic sources, but at the same time they are balanced out by various other natural processes.

6. What is the reason for extreme difference in temperatures at day and night in deserts?
a) Carbon dioxide concentrations are low in desert regions, therefore heat escapes easily
b) Sand has high heat conduction properties
c) Lack of moisture leads to escape of heat
d) All of the mentioned
Answer: c
Clarification: Lack of moisture, i.e. water vapour, prevents re-radiation of the IR rays from the surface, thereby not trapping heat. Hence desert has high temperatures during the day and extremely low temperatures in the night.

7. What does the method of “enhanced weathering” infer?
a) It is a method used to spray sulphate aerosols to reduce the greenhouse effect
b) It is a method of cloud seeding that is done to reduce the contribution of clouds to greenhouse effect
c) It is a method used to remove CO₂from the air
d) None of the mentioned
Answer: d
Clarification: Enhanced weathering is a form of geo-engineering where minerals are broken down to help remove CO2 from air.

8. What does the process of carbon sequestration mean?
a) Removal of CO₂ from the atmosphere
b) Storage of CO₂ by depositing in reservoir
c) Removal of CO₂ from the atmosphere & Storage of CO₂ by depositing in reservoir
d) None of the mentioned
Answer: c
Clarification: Carbon sequestration is the process of removal of CO₂ and storing them in carbon sinks to minimise their impact on global warming.

9. Which of the following is a sink for carbon?
a) Wetlands
b) Old oil fields
c) Saline waterbodies
d) All of the mentioned
Answer: d
Clarification: Wetlands, old oil fields, saline waterbodies, etc. are important carbon storages and help in removal of CO2 from atmosphere.

10. Which of the following greenhouse gas is contributed by cattle farming?
a) Nitrous oxide
b) Methane
c) Carbon monoxide
d) All of the mentioned
Answer: b
Clarification: Methane is a gas released by the digestive processes of cattle and hence cattle farming also contribute to greenhouse effect.

11. Volcanic eruptions contribute to the global greenhouse phenomenon.
a) True
b) False
Answer: b
Clarification: Volcanic eruptions release sulphate aerosols which help in blocking sun’s radiations from reaching the Earth’s surface. Hence they aid in generating a cooling effect.

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