Environmental Engineering Question Bank on “Dispersion of Air Pollutants, Contol of Gaseous Pollutants”.
1. When environmental Lapse Rate (ELR) is less is than Adiabatic Lapse Rate (ALR), then which of the following occurs?
a) Sub adiabatic lapse rate
b) Super adiabatic lapse rate
c) Neutral lapse rate
d) Adiabatic lapse rate
Answer: a
Clarification: When the temperature increases with an increase in altitude, Sub adiabatic lapse rate occur and there will be stable environment.
2. _______ occurs when atmospheric temperature increases with height.
a) Negative lapse rate
b) Super adiabatic lapse rate
c) Neutral lapse rate
d) Positive lapse rate
Answer: d
Clarification: Under negative lapse rate, the colder air is below the warmer air. It can be occurred near the earth’s surface.
3. When environmental Lapse Rate (ELR) is equal to the Adiabatic Lapse Rate (ALR), then which of the following occurs?
a) Sub adiabatic lapse rate
b) Super adiabatic lapse rate
c) Neutral lapse rate
d) Adiabatic lapse rate
Answer: c
Clarification: When the temperature is constant with height, then neutral lapse rate occurs.
4. The wet adiabatic rate is greater than the dry adiabatic rate.
a) True
b) False
Answer: b
Clarification: The value of wet adiabatic rate is 60C per 1000m whereas of dry adiabatic rate is 9.80C per 1000m.
5. When Environmental Lapse Rate (ELR) is greater than Adiabatic Lapse Rate (ALR), then which of the following occurs?
a) Sub adiabatic lapse rate
b) Super adiabatic lapse rate
c) Neutral lapse rate
d) Adiabatic lapse rate
Answer: b
Clarification: In Super adiabatic lapse rate, the environment is unstable due to the quick dispersion of pollutants.
6. Which of the following is the absorption unit?
a) Cyclone collector
b) Plate tower
c) Gravitation settling chamber
d) Dynamic precipitator
Answer: b
Clarification: Cyclone collector, Gravitation settling chamber and Dynamic precipitator are used to remove particulate matter, whereas Plate tower is used to remove gaseous matter and is an absorption unit.
7. Which of the following catalyst is used for removing hydrocarbon from gaseous pollutant in combustion unit?
a) Platinum
b) Activated alumina
c) Vanadium
d) Potassium permanganate
Answer: b
Clarification: Activated alumina is used as a catalyst for removing gaseous pollutant called hydrocarbons from the air. The concentration of hydrocarbon emitted from automobiles is 300-1000 mg/l.
8. Which of the following is not a part of adsorption unit?
a) Packed towers
b) Multiple fixed bed
c) Fluidized bed
d) Moving bed
Answer: a
Clarification: Packed tower is a part of the absorption unit, whereas multiple fixed bed, fluidized bed and moving bed are the examples of absorbers.
9. Which of the following is a bulk phenomena?
a) Physical adsorption
b) Chemical adsorption
c) Absorption
d) Sorption
Answer: c
Clarification: Adsorption is a bulk phenomena, whereas absorption is a surface phenomena.
10. Which of the following is not an adsorbent?
a) Molecular sieves
b) Activated carbon
c) Activated alumina
d) Water
Answer: d
Clarification: Water is an absorbent whereas molecular sieves, activated carbon and activated alumina are adsorbents.