Which one of the following gases is not responsible for global warming ?

Global warming is caused by Greenhouse Gases (GHGs) that trap infrared radiation in the atmosphere. The primary GHGs include carbon dioxide (CO₂), methane (CH₄), water vapour, nitrous oxide (N₂O), and chlorofluorocarbons (CFCs).

• Water vapour is the most abundant greenhouse gas and a major contributor to the natural greenhouse effect.
• Methane is a potent GHG with a much higher global warming potential than CO₂.
• CFCs are synthetic compounds that not only deplete the ozone layer but are also extremely effective at trapping heat.

Nitrogen (N₂), which constitutes about 78% of the atmosphere, is not a greenhouse gas. Because N₂ is a homonuclear diatomic molecule, it does not possess a dipole moment and cannot absorb the infrared radiation emitted by the Earth, meaning it does not contribute to global warming.