Which gas is NOT a greenhouse gas?

The chosen answer is accurate because nitrogen is not classified as a greenhouse gas. Greenhouse gases are those that trap heat in the atmosphere and contribute to the greenhouse effect, which is responsible for global warming and climate change. Carbon dioxide, methane, and ozone all have properties that allow them to absorb and emit infrared radiation, thus contributing to the warming of the Earth.

Nitrogen, on the other hand, makes up a significant portion of the Earth's atmosphere (about 78%) but does not have the capacity to absorb infrared radiation in the way that greenhouse gases do. It is considered a diatomic molecule and remains relatively inert in chemical reactions under normal atmospheric conditions, which is why it does not participate in the greenhouse effect.

The other gases listed are significant contributors to climate change: carbon dioxide is released through human activities such as fossil fuel combustion, methane has a much stronger heat-trapping ability than carbon dioxide albeit in smaller quantities, and ozone forms in the atmosphere and can also serve as a greenhouse gas. Therefore, nitrogen stands out as the gas that does not enhance the greenhouse effect.