Previous Year Question

Greenhouse Gases are gases that absorb and re-emit Infrared Radiation emitted by Earth's surface, thereby helping to retain heat in the atmosphere.

Carbon Dioxide (CO₂) is a major Greenhouse Gas. It is also part of the natural carbon cycle, but human activities such as fossil-fuel combustion, cement production and deforestation increase its atmospheric concentration.

Methane (CH₄) is also a powerful Greenhouse Gas. It enters the atmosphere through natural and anthropogenic processes including wetlands, livestock, rice cultivation, landfills and fossil-fuel extraction.

Chlorofluorocarbons (CFCs) are human-made gases and are also Greenhouse Gases. In addition to trapping heat, they have been associated with Stratospheric Ozone depletion. NASA also identifies CO₂, Methane and CFCs among Greenhouse Gases.

In contrast, Argon (Ar) is a chemically inert noble gas. It constitutes about 0.93% of Earth's dry atmosphere, but under normal atmospheric conditions it does not effectively absorb infrared radiation and is therefore not considered a Greenhouse Gas.