Engineering Questions with Answers - Multiple Choice Questions

Environmental Engineering MCQ – Devices to Control Air Pollution

1 - Question

Which of the following is used in ceramic industries?
a) Electrostatic precipitator
b) Dynamic precipitator
c) Spray tower
d) Wet cyclonic scrubber

View Answer

Answer: b
Explanation: Dynamic precipitator is used in ceramics, woodworking industries. It uses centrifugal force to remove gaseous matter.




2 - Question

Wet scrubbers are classified into ____ types.
a) 2
b) 3
c) 5
d) 6

View Answer

Answer: b
Explanation: Web scrubbers are used to remove air pollutants and are classified into Spray towers, Wet cyclonic scrubber and Venturi scrubber.




3 - Question

The centrifugal collectors are classified into how many types?
a) 3
b) 4
c) 5
d) 2

View Answer

Answer: d
Explanation: The Centrifugal collectors are classified into the Cyclone collector and Dynamic precipitator.




4 - Question

Which of the following air pollution control device has maximum efficiency?
a) Electrostatic precipitator
b) Dynamic precipitator
c) Spray tower
d) Wet cyclonic scrubber

View Answer

Answer: a
Explanation: Electrostatic precipitator has the maximum efficiency among the rest with a value of 99%.




5 - Question

Which of the following fluid is used in web scrubbers?
a) Lime
b) MgSO4
c) NaCl
d) K2Cr2O7

View Answer

Answer: a
Explanation: Apart from lime, K2CO3, a slurry of MnO and MgO and water can be used in Web scrubber.




6 - Question

Which of the following is incorrect regarding the fabric filter?
a) They can remove very small particle
b) They are liable to chemical attack
c) They have low efficiency in comparison to venturi scrubber
d) They can handle large volume of gas at relatively high speed

View Answer

Answer: c
Explanation: The efficiency of Electrostatic precipitator is <99%, whereas the efficiency of Fabric filter is >99%.




7 - Question

Which of the following removes both gaseous and particulate contaminants?
a) Venturi scrubber
b) Gravitational settling chamber
c) Dynamic precipitator
d) Wet scrubber

View Answer

Answer: a
Explanation: Venturi scrubber removes both gaseous and particulate contaminants. The minimum particle size removal is 0.5μm and its efficiency is < 99%.




8 - Question

Identify the correct statement regarding the Electrostatic precipitator.
a) Minimum particle size removal is <0.5μm
b) They can be operated at high temperature
c) It has a low maintenance cost
d) It does not cause any freezing problem

View Answer

Answer: b
Explanation: Electrostatic precipitator can be operated at a high temperature between 3000C to 4500C, has a high maintenance cost, can cause a freezing problem and minimum particle size removal is < 1μm.

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