Which one among the following substances is NOT a ‘green house’ gas ?

Greenhouse gases (GHGs) are atmospheric gases that absorb and re-emit infrared radiation, thereby trapping heat in the Earth's atmosphere [1]. Major greenhouse gases include water vapour, which is the most abundant and a significant contributor to the greenhouse effect [3], carbon dioxide, methane, and chlorofluorocarbons (CFCs) [2]. Methane and CFCs are particularly potent GHGs with high global warming potential [4]. In contrast, nitrogen (N2) is the primary component of dry air, making up approximately 78.08% of the atmosphere [5]. Unlike greenhouse gases, diatomic nitrogen does not absorb infrared energy effectively [5]. While nitrogen-based compounds like nitrous oxide (N2O) are powerful greenhouse gases [4], elemental nitrogen itself is not classified as a greenhouse gas. Therefore, nitrogen is the correct answer as it does not contribute to the greenhouse effect.

Sources

1. [1] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 7: Climate Change > 2. greenhouse gases > p. 9
2. [3] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > r7.3.r. Water vapour > p. 255
3. [2] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 11: World Climate and Climate Change > Greenhouse Gases(GHGs) > p. 96
4. [4] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 29: Environment Issues and Health Effects > Greenhouse gases (GHGS) > p. 426
5. [5] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 20: Earths Atmosphere > 20.1. Composition of The Earth's Atmosphere > p. 270