Which among the following are natural greenhouse gases (GHGs)? A. CO2 (Carbon…
2023
Which among the following are natural greenhouse gases (GHGs)?
A. CO2 (Carbon dioxide)
B. H2O (Water vapour)
C. CH4 (Methane)
D. O3 (Ozone)
E. CFC (Chlorofluorocarbon)
Choose the correct answer from the options given below:
Answer: A. A, B, C, D only — ConceptA greenhouse gas absorbs and re-emits outgoing infrared radiation, thereby warming the lower atmosphere. A gas may occur naturally even when human…
- A.
A, B, C, D only
- B.
A, C, D, E only
- C.
B, C, D, E only
- D.
A, B, C, E only
Show answer & explanation
Correct answer: A
Concept
A greenhouse gas absorbs and re-emits outgoing infrared radiation, thereby warming the lower atmosphere. A gas may occur naturally even when human activity also increases its concentration.
Naturally occurring greenhouse gases include water vapour, carbon dioxide, methane and ozone. Chlorofluorocarbons are synthetic industrial compounds rather than naturally occurring atmospheric gases.
Application
Carbon dioxide occurs naturally through respiration, decomposition, ocean-atmosphere exchange and volcanic activity.
Water vapour is a natural part of the water cycle and is the atmosphere’s most abundant greenhouse gas.
Methane has natural sources such as wetlands and microbial decomposition under oxygen-poor conditions.
Ozone occurs naturally in the stratosphere and also acts as a greenhouse gas.
CFCs were manufactured for uses such as refrigeration and aerosol propellants; they are not natural greenhouse gases.
Contrast and cross-check
The classification depends on natural occurrence, not merely on greenhouse effect. All five substances can influence radiation, but CFC is the synthetic member of the list. Therefore, the natural set is carbon dioxide, water vapour, methane and ozone.