Which gas is NOT considered a major greenhouse gas?

Which gas is NOT considered a major greenhouse gas?

• A. Water Vapour
• B. Carbon Dioxide
• C. Methane
• D. Oxygen

Answer: (D)

Gas molecules that trap heat in the atmosphere are greenhouse gases because they absorb infrared radiation and slow the loss of heat from Earth. Water vapor, carbon dioxide, and methane do this effectively, even at varying concentrations, making them major players in the greenhouse effect. Oxygen doesn’t fit this because O2 is a symmetric diatomic molecule with no permanent dipole moment, so its vibrational modes don’t absorb infrared radiation well. Without that infrared absorption, oxygen doesn’t contribute significantly to trapping heat, so it’s not considered a major greenhouse gas.

Gas molecules that trap heat in the atmosphere are greenhouse gases because they absorb infrared radiation and slow the loss of heat from Earth. Water vapor, carbon dioxide, and methane do this effectively, even at varying concentrations, making them major players in the greenhouse effect. Oxygen doesn’t fit this because O2 is a symmetric diatomic molecule with no permanent dipole moment, so its vibrational modes don’t absorb infrared radiation well. Without that infrared absorption, oxygen doesn’t contribute significantly to trapping heat, so it’s not considered a major greenhouse gas.