Previous Year Question

Greenhouse Gases are atmospheric gases that contribute to warming the atmosphere by absorbing and re-emitting Infrared Radiation emitted from the Earth's surface. This process is known as the Greenhouse Effect. Major greenhouse gases include Carbon Dioxide (CO₂), Methane (CH₄), Nitrous Oxide (N₂O), Water Vapour (H₂O), Ozone (O₃), and certain fluorinated gases.

Nitrogen (N₂) is not a greenhouse gas, although it constitutes approximately 78% of the Earth's atmosphere. Nitrogen is a Diatomic gas composed of two identical atoms. Its molecular vibration does not produce a change in the Electric Dipole Moment; therefore, it does not effectively absorb infrared radiation under ordinary atmospheric conditions. Consequently, Nitrogen does not produce a direct greenhouse effect.

All three other options are greenhouse gases. Carbon Dioxide (CO₂) increases mainly due to activities such as fossil fuel combustion and deforestation. Methane (CH₄) is emitted from livestock farming, rice cultivation, wetlands, and the production and transportation of fossil fuels. Nitrous Oxide (N₂O) is primarily released through microbial processes in agricultural soils, the application of nitrogen-based fertilizers, and certain industrial activities.

The distinction between Nitrogen (N₂) and Nitrous Oxide (N₂O) is important. Nitrogen is a common atmospheric gas, whereas Nitrous Oxide is a powerful greenhouse gas. Over a 100-year period, the Global Warming Potential (GWP) of Nitrous Oxide is approximately 273 times that of Carbon Dioxide. Thus, not all nitrogen-containing gases are greenhouse gases; their effects depend on their molecular structure and ability to absorb infrared radiation.