2.12d: demonstrate an understanding that H2O, CO2, CH4 and NO molecules absorb IR radiation and are greenhouse gases, whilst O2 and N2 are not

H2O, CO2, CH4, and NO molecules are able to absorb IR as they are able to change their polarity as they vibrate. This makes them greenhouse gases, as they are able to absorb and reradiate infrared radiation from the Sun back towards the Earth. O2 and N2 are not greenhouse gases as they are not able to absorb infrared radiation.