This set of Pollution Control Multiple Choice Questions & Answers (MCQs) focuses on “Behaviour of Air Pollutants – Set 2”.
1. Which of the following may be a reason for departure from stoke’s law?
a) Regular particle shapes
b) Variable particle shapes
c) High particle density
d) Air density
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Explanation: Stoke’s law is applied to regularly shaped particles. Air density and particle density are considered in its application. The departure of particle shapes from regular ones is a reason for the deviation from the law itself.
2. What is the mechanism of impact of particles in dry removal from the atmosphere?
a) Particles impact a surface and get deposited
b) Particles strike clouds and then rain out
c) Particles impact the ground as raindrops
d) Particles strike other particles in the air
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Explanation: When it comes to dry removal by impact, particles impact the surfaces at high velocities and settle on them. The other options listed involve wet removal from the atmosphere. Particles colliding does not warrant falling on the ground.
3. Which of the following is not a sink for air pollutants?
a) The soil
b) The ocean
c) The fauna
d) The flora
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Explanation: Air pollutants get transported to the earth’s surface, where the soil, ocean, or plants can absorb them. Not all the natural sources absorb every air pollutant though. For example, the ocean absorbs sulphur dioxide, the soil acts as a carbon monoxide sink, et cetera.
4. The ocean takes up sulphur dioxide by which process?
a) Precipitation
b) Chemical reaction
c) Adsorption
d) Absorption
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Explanation: The ocean absorbs sulphur dioxide. The mechanism involves the diffusion of sulphur dioxide through the gas-liquid interface from the gas phase to the liquid phase. Then it is absorbed by the bulk of the ocean.
5. Which process is responsible for plants acting as a sulphur dioxide sink?
a) Adsorption
b) Absorption
c) Chemical reaction
d) Precipitation
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Explanation: Sulphur dioxide gets adsorbed on the surface of the plants. It diffuses to the surface of the plant leaf, where it gets adsorbed at the pores. Alternatively, sulphur dioxide gets absorbed by oceans.
6. The soil is a carbon monoxide sink. Which process is the reason for this?
a) Absorption
b) Biological reaction
c) Adsorption
d) Chemical reaction
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Explanation: The bacteria present in the soil utilise atmospheric carbon monoxide, thus making soil a sink. In the biological reaction, the conversion of carbon monoxide to either carbon dioxide or methane is done by bacteria.
7. Sulphur dioxide is rapidly converted to sulphur trioxide in the atmosphere in the presence of a catalyst. Which of the following is a catalyst?
a) Water
b) Titanium salts
c) Iron salts
d) Oxygen
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Explanation: Sulphur dioxide gets oxidised to sulphur trioxide in the presence of catalysts. These catalysts are metal salts that act as the reaction centres. Examples of metal salts are iron salts.
8. Sulphur dioxide is indirectly converted to which of the following aerosols in the atmosphere?
a) Sulphur trioxide
b) Sulphates
c) It does not react in the atmosphere
d) Sulphuric acid
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Explanation: Sulphur dioxide is converted indirectly to sulphuric acid in the atmosphere, with sulphur trioxide as the intermediate. Sulphur trioxide is not an aerosol, and sulphates are produced from sulphur dioxide.
9. Which of the following does not oxidise nitrogen dioxide to nitric acid in the atmosphere?
a) Metal oxides
b) Free radicals
c) Nascent oxygen
d) Ozone
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Explanation: The oxidation of nitrogen dioxide to nitric acid is a slow process. Faster reactions occur in the presence of oxidants like ozone, nascent oxygen and free radicals present in the atmosphere.
10. In the atmosphere, which chemical reaction is a significant carbon monoxide sink?
a) Reaction with oxygen
b) Reaction with OH radical
c) Reaction with Water vapour
d) Reaction with nascent oxygen
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Explanation: A significant carbon monoxide sink in the atmosphere is the reaction of carbon dioxide with hydroxyl free radicals. Although carbon monoxide does react with oxygen, the reaction is slow and does not significantly reduce the concentration of carbon monoxide in the atmosphere.
11. Which of the following is not an ideal circumstance for smog formation?
a) High concentration of NOX
b) Dormant air
c) Low concentration of hydrocarbons
d) Sunlight
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Explanation: High concentrations of both NOX and hydrocarbons are necessary for smog formation since more reactants yield more products. Calm weather conditions in sunny regions also tend to accelerate its formation.
12. Where does smog occur in the presence of sunlight?
a) Lower atmosphere
b) Higher atmosphere
c) Cloudy regions
d) During rainfall
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Explanation: Photochemical smog occurs in the presence of sunlight. The reactions to produce smog also occur in the lower atmosphere. These same reactants would react differently in the upper atmosphere.
13. What is the role of sulphur dioxide and carbon monoxide in smog formation?
a) Retardant
b) Accelerant
c) No effect
d) Inhibitor
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Explanation: Studies have shown that the presence of sulphur dioxide and carbon monoxide act as accelerants. They accelerate the oxidation processes in smog. For example, CO accelerates the oxidation of NO.
14. Under which of the following conditions is smog most likely to form?
a) Windy cloudy day
b) Rainy day
c) Calm sunny day
d) Windy sunny day
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Explanation: Smog is most likely to occur on a calm sunny day. The statement is true because the ideal conditions for smog formation are still air. Sunlight is a catalyst so smog cannot form in its absence.
15. The control of smog formation can be done by which of the following actions?
a) Control sulphur dioxide emissions
b) Control hydrocarbon emissions
c) Control NOX emissions
d) Control NOX and hydrocarbon emissions
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Explanation: The control of both hydrocarbon and nitrogen oxide emissions can control the formation of smog. Control of one or the other is not enough. Sulphur dioxide control is helpful, but not as significant.
Sanfoundry Global Education & Learning Series – Pollution Control.
To practice all areas of Pollution Control, here is complete set of 1000+ Multiple Choice Questions and Answers.
