Which of the following is not a greenhouse gas?

The correct answer is O₂.

Key Points

• NO₂ is not considered a greenhouse gas because it does not significantly absorb and trap heat in the Earth's atmosphere.
• Greenhouse gases are responsible for the greenhouse effect, which warms the Earth's surface by trapping heat.
• Examples of greenhouse gases include CO₂, CH₄, N₂O, O₃, and CFCs.
• Although NO₂ contributes to air pollution and acid rain, its role in trapping heat is negligible compared to major greenhouse gases.

Additional Information

• O₃ (Ozone): Ozone is a greenhouse gas that exists in the Earth's stratosphere and troposphere. While stratospheric ozone protects us from harmful ultraviolet radiation, tropospheric ozone acts as a greenhouse gas by trapping heat.
• N₂O (Nitrous Oxide): Nitrous oxide is a potent greenhouse gas that is released primarily from agricultural practices, fossil fuel combustion, and industrial processes. It has a global warming potential (GWP) significantly higher than CO₂.
• NO₂ (Nitrogen Dioxide): Although NO₂ is a significant air pollutant that contributes to smog and acid rain, it is not considered a major greenhouse gas. It does not have a significant heat-trapping effect in the atmosphere.
• CFCs (Chlorofluorocarbons): CFCs are synthetic compounds that act as strong greenhouse gases. They were widely used in refrigeration, air conditioning, and aerosol sprays. Due to their role in ozone depletion, their production has been phased out under the Montreal Protocol.