Which of the gas is not known as green house gas?

Answer: Option D

Greenhouse gases include: Water vapour (H₂O), Carbon dioxide (CO₂), Methane (CH₄), Nitrous oxide (N₂O), Ozone (O₃), and Fluorinated gases such as CFCs, HFCs, PFCs, and SF₆.

Hydrogen (H₂) is not a greenhouse gas because it has no permanent electric dipole moment and therefore does not absorb infrared (IR) radiation effectively. The greenhouse effect occurs when gases absorb and re-emit infrared radiation emitted by Earth’s surface. Since hydrogen cannot interact with IR radiation in this way, it does not contribute to atmospheric warming.

Furthermore, hydrogen is a very light gas that tends to escape into the upper atmosphere, preventing its accumulation in significant amounts to influence Earth’s temperature.