This set of Pollution Control Multiple Choice Questions & Answers (MCQs) focuses on “Characteristics of Gaseous Pollutants – Set 2”.
1. In the following given options, which air pollutant is the most concentrated in the atmosphere?
a) Carbon monoxide
b) Particulates
c) Sulphur dioxide
d) Nitrogen dioxide
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Explanation: Among the given options, carbon monoxide has the highest concentration in the atmosphere. The reason for it is the high demand for fuel consumption. Contrarily, Nitrogen dioxide is the least.
2. Which of the following statements about carbon monoxide is untrue?
a) It is odourless
b) It has a pungent odour
c) It is tasteless
d) It is colourless
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Explanation: The question is asking for a false statement in regards to carbon dioxide. Carbon monoxide is a colourless and tasteless. Since carbon monoxide is odourless, it does not have a pungent odour unlike stated.
3. How fast is the rate at which carbon monoxide gets converted to carbon dioxide?
a) Moderately fast
b) Slowly
c) Very slowly
d) Very fast
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Explanation: Studies have shown that the rate at which carbon monoxide converts to carbon dioxide is very slowly. Even in the presence of oxygen and sunlight, only a small percentage of carbon monoxide gets oxidised.
4. Carbon dioxide forms which of the following secondary pollutants in the atmosphere?
a) Benzene
b) Methane
c) PAN
d) Ozone
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Explanation: In photochemical smog, carbon monoxide forms both from carbon dioxide and ozone. These reactions occur in the presence of sunlight. Additionally, ground-level ozone may be produced by NOx.
5. Which of the following air pollutants does not result in the formation of ground-level ozone?
a) Nitrogen dioxide
b) Sulphur dioxide
c) Terpene
d) Carbon monoxide
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Explanation: Nitrogen dioxide, carbon monoxide, and terpenes result in the formation of ground-level ozone. This reaction is an oxidation reaction which occurs in the presence of sunlight. Sulphur dioxide is the odd one out.
6. Which saturated hydrocarbon is the most abundant hydrocarbon greenhouse gas?
a) Propane
b) Butane
c) Methanol
d) Methane
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Explanation: Methane is the saturated hydrocarbon that is the most abundant hydrocarbon air pollutant. Its main sources include marshes and the cattle grazing. Since it is saturated, it is not as reactive in the atmosphere.
7. Of the total hydrocarbon presence in the atmosphere, approximately how much is methane?
a) 10%
b) 30%
c) 60%
d) 90%
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Explanation: Methane is the most abundant hydrocarbon air pollutant in the atmosphere. About 40% to 80% of all the atmospheric hydrocarbon concentration is methane. Among the given options, only 60% falls in this range.
8. Which of the following unsaturated hydrocarbons are the most prominent air pollutants?
a) Ethylene only
b) Propene only
c) Ethylene and propene
d) Methane only
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Explanation: Both ethylene and propene are important air pollutants. Although they pollute the atmosphere, their concentration is significantly less when compared to methane, a saturated hydrocarbon.
9. Benzene is the most prominent aromatic hydrocarbon air pollutant.
a) True
b) False
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Explanation: Benzene may high have a high concentration in the urban areas, but there are other aromatics with higher concentrations in the atmosphere. Such hydrocarbons are toluene and xylene.
10. Which of the following hydrocarbons are emitted primarily by natural sources?
a) Methane
b) PAN
c) Terpenes
d) Hydrogen sulphide
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Explanation: Terpenes are released primarily from natural sources, while methane is released from both primary and anthropogenic sources. PAN is formed in photochemical smog, and is a secondary pollutant.
11. Methane is an air pollutant.
a) True
b) False
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Explanation: Methane mainly falls into the category of greenhouse gases since it absorbs longwave radiation. Moreover, methane is a saturated hydrocarbon, so it has a low reactivity in the atmosphere.
12. Why is the presence of hydrocarbons in the atmosphere so concerning?
a) They are harmful health effects
b) They cause the greenhouse effect
c) Their concentrations are high
d) They form secondary pollutants
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Explanation: Unsaturated hydrocarbons produce harmful secondary pollutants in the atmosphere in the presence of sunlight. An example is NOx and VOCs reacting to produce ground-level ozone.
13. Which of the following hydrocarbons is not very reactive?
a) Xylene
b) Propene
c) Terpenes
d) Methane
View Answer
Explanation: All the given options, except methane, are unsaturated hydrocarbons. Saturated hydrocarbons have low reactivity due to their complete bonds. This property is significant for methane to not be considered as an air pollutant.
Sanfoundry Global Education & Learning Series – Pollution Control.
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