Category: Environmental Engineering Objective Questions

Environmental Engineering Multiple Choice Questions on “Reciprocating Pump”.

1. The reciprocating pump has a ______ flow.
a) Pulsating
b) Uniform
c) Continuous
d) Constant
Answer: a
Clarification: The reciprocating pump has a continuous flow. It has a constant discharge even if head on the delivery side varies.

2. The speed at which the reciprocating pump runs (in m/min) is _____________
a) 28
b) 90
c) 100
d) 120
Answer: a
Clarification: The reciprocating pump runs at a low speed. Its speed is less than 30m/min. If they are connected to driving machines, speed reducing devices are necessary.

3. The maximum efficiency of a reciprocating pump is _____________
a) 50%
b) 60%
c) 85%
d) 100%
Answer: c
Clarification: The efficiency of the reciprocating pump lies between 40% and 85%. Long stroke engines have 85% efficiency while smaller pumps have 40%.

4.In which type of pump, the liquid is in contact with both sides of the plunger?
a) Single acting reciprocating pump
b) Double acting reciprocating pump
c) Single cylinder pump
d) Booster pump
Answer: b
Clarification: At the double acting reciprocating pump, the liquid is in contact with both sides of the plunger. It has two suction and deliver pipes having appropriate valves.

5. Based on the number of cylinders, the reciprocating pump is divided into ____ types.
a) 2
b) 3
c) 4
d) 5
Answer: d
Clarification: the reciprocating pump is divided into 5 types on the basis of number of cylinders. It includes single cylinder, double cylinder, triple cylinder, duplex double action and quintuplex pump.

6. Which type of reciprocating pump has a 1200 crank?
a) Single cylinder pump
b) Double cylinder pump
c) Triple cylinder pump
d) Duplex double action pump
Answer: c
Clarification: In a Triple cylinder reciprocating pump, each cylinder has its own suction and delivery pipes and has a 1200 crank.

7. Quintuplex pump has a crank of ____
a) 60^o
b) 72^o
c) 120^o
d) 1800^o
Answer: b
Clarification: Quintuplex pump has five single acting cylinders with separate suction and delivery having 72^o crank.

8. The number of valves required in rotary pump is _____________
a) 0
b) 1
c) 2
d) 3
Answer: a
Clarification: No valves are required in rotary pump and the flow is continuous. Gear, Lobe and Vane pumps are the examples of rotary pump.

9. Consider the following statement regarding Reciprocating pump.
i. High initial cost
ii. Requires a small space
iii. Less power required
Which of the following is/are incorrect statements?
a) Only 1
b) Only 2
c) Only 3
d) 2, 3
Answer: d
Clarification: The reciprocating pump has high initial and maintenance cost, more power required and required large space.

Environmental Engineering Multiple Choice Questions on “Types of Sewers”.

1. Which type of sewer serves as an outlet for large territory?
a) Lateral sewer
b) Main sewer
c) Branch sewer
d) Separate sewer
Answer: b
Clarification: Main sewer acts as an outlet for the large territory as it receives sewage from many tributary branches.

2. Which sewer collects sewage directly from the house?
a) Main sewer
b) Outfall sewer
c) Lateral sewer
d) Intercepting sewer
Answer: c
Clarification: The first stage of collection of sewage starts from the house which is done by Lateral sewer.

3. _______ sewer collects sewage from collecting system to a disposal plant?
a) House sewer
b) Outfall sewer
c) Lateral sewer
d) Separate sewer
Answer: b
Clarification: The Outfall sewer is a sewer that carries the sewage from collecting systems and transfers it to a point of final discharge i.e a disposal plant.

4. Which sewer carries both sewage and storm water?
a) Outfall sewer
b) Separate sewer
c) Main sewer
d) Combined sewer
Answer: d
Clarification: Combined sewer carries both the sewage and the rain water from the roofs of the house and from the street.

5. Which sewer is also called as submain sewer?
a) Branch sewer
b) Separate sewer
c) Main sewer
d) Lateral sewer
Answer: a
Clarification: Submain sewer receives sewage from small area which finally get discharged into the main sewer. It is also called as branch sewer.

6. Which sewer is used to carry the excess flow of existing sewer?
a) Branch sewer
b) Relief sewer
c) Main sewer
d) Lateral sewer
Answer: a
Clarification: The Relief sewer is used to carry the excess flow of the existing sewer. It is also called as overflow sewer.

7. Asbestos cement sewers are made from __________
a) Cement, silica
b) Asbestos fibre, copper
c) Asbestos fibre, cement, silica
d) Asbestos fibre, magnesium
Answer: c
Clarification: Asbestos cement sewers are made from the composition of asbestos fibre, cement, silica asbestos fibre acts as a reinforcing material.

8. Which of the following is a disadvantage of asbestos cement sewer?
a) They are light weight
b) They can be easily jointed
c) They are brittle
d) Inside surface is smooth
Answer: c
Clarification: Asbestos cement sewer is weak against the impact force and requires care in handling.

9. Asbestos cement sewer offers resistant to sulfide corrosion.
a) True
b) False
Answer: b
Clarification: Asbestos cement sewer is used as verticals only because they are prone to sulfide corrosion.

Global Education & Learning Series – Environmental Engineering .

Environmental Engineering Multiple Choice Questions on “Racks and Screen”.

1. The minimum spacing between the bars on fine screen is ____________
a) 0.3mm
b) 0.9mm
c) 1.5mm
d) 0.5mm
Answer: c
Clarification: The range of space between the bars in fine screen is 1.5-3mm having minimum spacing as 1.5mm.

2. The spacing between the bars in racks is ____________
a) 30mm
b) 50mm
c) 70mm
d) 90mm
Answer: b
Clarification: The spacing between the bars in racks is 50mm. It is commonly called as coarse screen.

3. Screens are inclined to the direction of flow to ____________
a) Increase the flow velocity
b) Increase the opening area
c) Decrease the flow velocity
d) Increase the head loss
Answer: c
Clarification: Screens are inclined to the direction of flow to decrease the flow velocity in order to increase the efficiency of the screen.

4. The maximum spacing between the bars in medium screen is ____________
a) 40mm
b) 50mm
c) 70mm
d) 90mm
Answer: a
Clarification: The range of space between the bars in fine screen is 7-40mm having maximum spacing as 40mm.

5. __________ is used to cut the sewage into smaller parts.
a) Flocculator
b) Tube settlers
c) Shredders
d) Aerators
Answer: c
Clarification: Shredder is a device which is used to cut large size sewage particles into a smaller size. It is composed of screens and cutting teeth.

6. What is the maximum capacity of medium screen in collecting solids?
a) 30L
b) 40L
c) 50L
d) 90L
Answer: d
Clarification: Medium screen can collect up to the maximum capacity of 90L of solids per 106 L of effluent.

7. The head loss through the screen is given by HL = k* (Vt2 – Va2), where Vt and Va are velocities through and above the screen respectively. What is the value of constant k?
a) 1
b) 0.0050
c) 0.0729
d) 0.0236
Answer: c
Clarification: The expression for the head loss through the screen is given by
HL = 0.0729* (V_t² – Va²), where Vt and Va are the velocities through and above the screen respectively.

Environmental Engineering Multiple Choice Questions on “Construction of Imhoff Tank”.

1. Which of the following is represented by C in the following figure?

Figure: Imhoff tank
a) Outlet
b) Digestion chamber
c) Gas chamber
d) Sedimentation chamber
Answer: b
Clarification: C represents the digested chamber. It is placed in the lower section of Imhoff tank.

2. In which of the following, the settling of solids takes place in the following figure?

Figure: Imhoff tank
a) Outlet
b) Digestion chamber
c) Gas chamber
d) Sedimentation chamber
Answer: d
Clarification: The settling of solids takes place at the sedimentation chamber. It is represented by D in the above figure.

3. The maximum flow through the period at D in the following figure?

Figure: Imhoff tank
a) 0.3m/min
b) 0.4m/min
c) 0.8m/min
d) 0.9m/min
Answer: a
Clarification: The maximum flow through the period at D is 0.3m/min and its design depth should be between 3 to 3.5 m.

4. The sludge is digested in which of the following?

Figure: Imhoff tank
a) Outlet
b) Sedimentation chamber
c) Gas chamber
d) Digestion chamber
Answer: d
Clarification: The sludge is digested in the digestion chamber. Its minimum design capacity is 57 liters per person.

5. The gas chamber in the below figure is represented by _____________

Figure: Imhoff tank
a) A
b) E
c) B
d) C
Answer: b
Clarification: The gas chamber is represented by the E in the figure. It is located at the sides of the Imhoff tank.

6. The sewage comes in the Imhoff tank through which of the following?

Figure: Imhoff tank
a) A
b) B
c) C
d) D
Answer: a
Clarification: A represents the inlet through which the sewage enters the Imhoff tank.

7. The detention period of the sedimentation chamber of an Imhoff tank is?

Figure: Imhoff tank
a) 30 seconds
b) 30 minute
c) 1 hour
d) 2 hours
Answer: d
Clarification: The detention period of the sedimentation chamber of an Imhoff tank is 2 hours. It is represented by D as shown in the figure.

8. B in the following figure is represented by ____________

Figure: Imhoff tank
a) Outlet
b) Sedimentation chamber
c) Gas chamber
d) Digestion chamber
Answer: a
Clarification: B represents the outlet of Imhoff tank. It carries the partially treated sewage.

9. Which of the following is called a scum chamber in the following figure?

Figure: Imhoff tank
a) Settling chamber
b) Sedimentation chamber
c) Gas chamber
d) Digestion chamber
Answer: c
Clarification: Gas chamber is also called a scum chamber. The minimum design width of the gas chamber is 60cm.

Environmental Science Multiple Choice Questions on “Greenhouse Gases – 1”.

1. By how much has atmospheric carbon dioxide concentration increased ever since the Industrial Revolution?
a) 20%
b) 10%
c) 40%
d) 60%
Answer: c
Clarification: Due to excessive combustion of fossil fuels, the carbon dioxide concentration shot up from 280ppm during 1750 to nearly 400ppm recently.

2. Which is the most abundant greenhouse gas in the atmosphere?
a) Carbon dioxide
b) Water vapour
c) Methane
d) Nitrogen
Answer: b
Clarification: Water vapour also helps in trapping sun’s heat energy and thereby serves as the most abundant greenhouse gas.

3. What does the phrase “anthropogenic CO₂ emissions” mean?
a) Human made CO₂ emissions
b) Industrial CO₂ emissions
c) Natural CO₂ emissions
d) All of the mentioned
Answer: a
Clarification: The word “anthropogenic” stands for environmental impact due to human activity.

4. Which of the following is the largest sink for carbon dioxide gas?
a) Forests
b) Oceans
c) Ice sheets
d) Grasslands
Answer: b
Clarification: Carbon dioxide dissolves in water as not only gas but also in the bicarbonates form. Therefore, ocean is one of the major sinks for carbon dioxide.

5. Apart from Earth, which other celestial body(s) exhibits greenhouse gas effect?
a) Venus
b) Mars
c) Titan
d) All of the mentioned
Answer: d
Clarification: Titan, Mars and Venus contain several greenhouse gases in their atmosphere and exhibit greenhouse effect.

6. Which of the following bodies in the solar system has anti-greenhouse effect?
a) Jupiter
b) Mars
c) Titan
d) Venus
Answer: c
Clarification: Titan also exhibits anti-greenhouse effect. The haze, constituting organic molecules, is not very efficient in trapping infrared radiations and thereby reduces the temperature by 9 K.

7. Which of the following radiations of the sun do greenhouse gases trap?
a) Visible radiations
b) Infrared radiations
c) UV radiations
d) All the radiations
Answer: b
Clarification: Greenhouse gases trap the infrared radiations from the sun and reflect it back to the Earth’s surface thereby heating up the planet.

8. What does “airborne fraction” with respect to greenhouse gases indicate?
a) Amount of greenhouse gases that are released into air due to industrial process
b) Proportion of greenhouse gases in air to all the other atmospheric gases
c) Proportion of greenhouse gas emission that remain even after a specified time
d) None of the mentioned
Answer: c
Clarification: The airborne fraction (AF) indicates the proportion of GHG emissions that remain after a given time.

9. Clouds help in cooling down the planet and do not contribute to greenhouse effect.
a) True
b) False
Answer: b
Clarification: Clouds can absorb infrared radiation as well as emit them and hence contribute to greenhouse effect.

10. What does GWP in the context of greenhouse gases indicate?
a) Global Warming Parameters
b) Gradual Warming Pattern
c) Global Warming Patterns
d) Global Warming Potential
Answer: d
Clarification: Global warming potential indicates the heat trapped by a greenhouse gas over 20, 50 or 100 years in terms of equivalent heat trapped by carbon dioxide over the same period of time.

11. What is the GWP of methane over a time period of 20 years?
a) 86
b) 34
c) 43
d) 67
Answer: a
Clarification: According to IPCC methane which has a 12.4 years lifetime, has a GWP of 86 over a period of 20 years.

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Environmental Engineering Multiple Choice Questions on “Various Unit Operations”.

1. In which unit operation, gases are released or absorbed in the water?
a) Gas transfer
b) Ion transfer
c) Solute stabilization
d) Solids Transfer
Answer: a
Clarification: In Gas transfer, gases are released or absorbed in water by exposing the water through aeration under normal, increased or reduced pressure.

2. How many types of aerators are commonly used in the treatment of water?
a) 2
b) 3
c) 4
d) 5
Answer: c
Clarification: There are 4 types of aerators namely Gravity aerators, Spray aerators, Diffusers and Mechanical aerators.

3. Which of the following process is used to remove the colloidal particles from water?
a) Chemical precipitation
b) Chemical coagulation
c) Ion exchange
d) Adsorption
Answer: b
Clarification: Chemical coagulation is used to remove colloidal particles by the use of coagulants which increase the particle size and they settle down.

3. Flocculation of iron from water by the addition of lime is an example of which of the following process?
a) Chemical precipitation
b) Chemical coagulation
c) Ion exchange
d) Adsorption
Answer: a
Clarification: Chemical precipitation removes the dissolved substance from water through ion transfer where precipitation of dissolved impurities takes place.

4. In which unit operation objectionable solutes are converted into unobjectionable forms without removal?
a) Gas transfer
b) Ion transfer
c) Solute stabilization
d) Solids Transfer
Answer: c
Clarification: In solute stabilization, water is stabilized by chlorination or liming so that objectionable solutes are converted into unobjectionable form.

5. In which form of solute stabilization, hydrogen sulfide in water is oxidized into sulfate?
a) Chlorination
b) Liming
c) Re-carbonation
d) Super-chlorination
Answer: a
Clarification: By the process of chlorination, water gets stabilized by the conversion of hydrogen sulfide into sulfate.

6. Which form of solute stabilization occurs when water passes through limestone?
a) Chlorination
b) Liming
c) Re-carbonation
d) Super-chlorination
Answer: b
Clarification: When water passes through limestone, carbon dioxide in excess get converted into soluble bicarbonate.

7. In which process, excess lime is converted into bicarbonate?
a) Chlorination
b) Liming
c) Re-carbonation
d) Super-chlorination
Answer: c
Clarification: By Re-carbonation of water softened by excess lime treatment, excess lime is converted into bicarbonate.

8. By which process, odour producing substances is oxidized?
a) Chlorination
b) Liming
c) Re-carbonation
d) Super-chlorination
Answer: d
Clarification: By addition of chlorine dioxide to water, odour producing substances are oxidized.

9. Solids are removed from the water by which of the following unit operation?
a) Inter facial contact
b) Solid stabilization
c) Ion transfer
d) Solids transfer
Answer: d
Clarification: During solids transfer, solids are removed from water by straining, sedimentation, flotation and filtration.

10. Dealkalization results in removal of all the ions from the water.
a) True
b) False
Answer: b
Clarification: Dealkalization results in removal of hydroxides, carbonates and bicarbonates of calcium, sodium and magnesium from water. Demineralization results in removal of all the ions from the water.

11. Organic contaminants are removed from the water by the process of ______
a) Water softening
b) Demineralization
c) Absorption
d) Adsorption
Answer: d
Clarification: Organic contaminants are removed from the water by the attraction and accumulation of one substance on the surface of another.