This set of Pollution Control Multiple Choice Questions & Answers (MCQs) focuses on “Greenhouse Effect”.
1. Greenhouse gases absorb which kind of radiation?
a) Long-wave radiation
b) Short-wave radiation
c) UV radiation
d) Visible light
View Answer
Explanation: Greenhouse gases absorb long-wave radiation, also known as infrared radiation. The earth absorbs solar radiation then emits heat of its own, which is in turn absorbed by greenhouse gases.
2. The greenhouse effect would still exist without the presence of the atmosphere.
a) True
b) False
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Explanation: The greenhouse effect is a natural phenomenon which occurs because the atmosphere exists. The atmosphere holds gases, which absorb radiation. This would not happen in the absence of an atmosphere. The issue is that these gases are now in excess due to human-made causes.
3. What would be the surface temperature of the earth without the atmosphere and the greenhouse effect?
a) Approximately 10 degrees Celsius
b) Approximately -10 degrees Celsius
c) Approximately -18 degrees Celsius
d) Approximately -28 degrees Celsius
View Answer
Explanation: The average temperature of Earth would drop from (12˚C – 14˚C) to as low as –18˚C, without the greenhouse effect. So, the surface temperatures would be approximately 30 degrees cooler without an atmosphere and the greenhouse effect. The greenhouse gases maintain ambient temperatures at the surface because of the greenhouse effect. However, uncontrolled heating may occur if these gases are present in excess.
4. Which greenhouse gas is the most effective?
a) Sulphur dioxide
b) Ozone
c) Carbon dioxide
d) Water vapour
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Explanation: Water vapour is the most effective greenhouse gas. This is because the heat capacity of water is high, allowing it to store a lot of heat. However, water vapour has a short lifetime, and factors like temperature govern its concentration in the atmosphere.
5. Which of the following is an example of industrial greenhouse gas?
a) Water vapour
b) Ozone
c) Sulphur hexafluoride
d) Methane
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Explanation: Sulphur hexafluoride is an industrial greenhouse gas. It is said to be more potent than carbon dioxide, but its concentration and lifetime in the environment are comparatively less. Unlike the other options, sulphur hexafluoride is not found naturally in the atmosphere.
6. What was the concentration of carbon dioxide in the atmosphere in pre-industrial times?
a) 350 ppm
b) 330 ppm
c) 300 ppm
d) 280 ppm
View Answer
Explanation: 280 ppm was the concentration of carbon dioxide in the atmosphere before the industrial revolution. This concentration remained constant for thousands of years. As of 2020, the concentration of carbon dioxide is close to 420 ppm.
7. Which of the following statements about methane is true?
a) Methane is a more effective greenhouse gas than carbon dioxide
b) Carbon dioxide is more effective greenhouse gas than methane
c) Methane is the most effective greenhouse gas
d) Carbon dioxide is the most effective greenhouse gas
View Answer
Explanation: The statement ‘methane is more effective than carbon dioxide as a greenhouse gas’ is true. The most effective greenhouse gas is not methane, but water vapour on account of its heat capacity.
8. Which of the following are methane sinks?
a) The atmosphere and the soil
b) The soil and the ocean
c) The oceans and the atmosphere
d) The oceans and the forests
View Answer
Explanation: The atmosphere and the soil are two methane sinks. In the atmosphere, methane either decomposes to carbon dioxide, or it reacts with the OH free radicals. In the soil, bacteria convert it to methanol.
9. Why is the lifetime of water vapour in the atmosphere short?
a) Its lifetime is long
b) It precipitates
c) It reacts with other gases
d) It cannot survive in the atmosphere
View Answer
Explanation: Unlike other greenhouse gases, there is a constrain on the concentration of water vapour in the atmosphere. The air can get saturated with water vapour at a particular temperature, due to which it precipitates as rain or snow. As the earth warms, the air will be able to hold more moisture on account of the temperature rise.
10. What is radiative forcing?
a) Difference between incoming solar radiation and heat radiation absorbed by gases
b) Difference between outgoing heat radiation and the heat radiation absorbed by gases
c) Difference between incoming solar radiation and outgoing heat radiation
d) Difference between heat radiation absorbed by gases and the outgoing heat radiation
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Explanation: Radiative forcing is the difference between the solar radiation incident on the earth’s surface and the outgoing heat radiation that the earth’s surface radiates. RF indicates how much of heat energy is retained by the atmosphere.
11. How much of the energy radiated by the earth’s surface is absorbed by the atmosphere?
a) About 60%
b) About 70%
c) About 80%
d) About 90%
View Answer
Explanation: About 90% of the heat energy radiated by the earth is absorbed by the gases in the atmosphere. It is because of the greenhouse effect that the particles in the atmosphere can do so.
12. Greenhouse gases absorb the heat radiation emitted by the earth’s surface. Then they re-radiate this energy they absorb.
a) True
b) False
View Answer
Explanation: Greenhouse gases do not absorb shortwave radiation (like UV radiation), instead they absorb longwave radiation (like IR radiation). Such radiations are emitted from the earth’s surface. Greenhouse gases re-radiate the IR radiations they absorb, causing further warming of the environment and the surface.
13. What is positive radiative forcing?
a) When the earth’s surface cools
b) When the earth’s surface warms
c) Radiative forcing has a positive effect on the environment
d) When there is no net change in the surface temperature
View Answer
Explanation: Radiative forcing is the difference between the solar radiation incident on the earth’s surface and the outgoing heat radiation that the earth’s surface radiates. Positive radiative forcing occurs when gases like greenhouse gases (or other factors) cause warming of the earth’s surface.
14. Climate sensitivity is used to relate which parameters?
a) Global warming and greenhouse effect
b) Global warming and surface temperatures
c) Radiative forcing and surface temperatures
d) Radiative forcing and greenhouse effect
View Answer
Explanation: Some factors affect the radiation balance of the atmosphere, which in turn affects the surface temperatures. As a result, surface temperatures either warm or cool. Climate sensitivity is a way to relate these two.
15. What is negative radiative forcing?
a) It negatively affects the earth’s surface
b) It occurs because of more incident sunlight
c) It results in the warming of the earth’s surface
d) It results in the cooling of the earth’s surface
View Answer
Explanation: When the earth’s radiation balance is affected, the earth’s surface either warms or cools. Negative radiative forcing causes the surface temperatures to cool. An example of materials causing this is sulphate aerosols, which tend to reflect sunlight and cause cooling of the atmosphere.
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.
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