Question

Does either Ar or CO absorbs thermal IR?

which of the greenhouse gases absorbs thermal IR?

what are the two main anthropogenic sources of carbon dioxide in the atmosphere?

what are the two main sinks of atmospheric carbon dioxide?

Answer 1

1. Ar or CO do not absorb thermal IR.

Thermal infared: It is electromagnetic radiation with wavelengths longer than those of visible light. It is invisible to the human eye but you can feel it. Most of the thermal radiation emitted by objects near room temperature is infrared.

In order to absorb thermal IR there should be change in dipole moment through vibrational motion which is in the molecules containing 3 or more atoms. As Ar and CO contains two atoms and moreover Ar does not have vibrational modes so they dont observe any change in their dipole moment hence do not absorb thermal IR energy.

2. Greenhouse gases which absorb thermal IR are:

Green house gases are those gases which absorb and emits the energy within thermal infrared region.

Gases which do so are:

CO2, CH4, N2O, H2O

3. Anthropogenic sources of carbon dioxide in nature.

Anthropogenic means the things generated by human beings. Here it means the source of carbon dioxide generated by human beings.

Sources are:

(a) Burning of fossil fuels (coal, oil, natural gas) which emit CO2 as a by product.

(b) CO2 produced from industrial sources, transportation, agriculture also contributes.

(c) Deforestation is also the source, because of less trees CO2 is increasing in nature as they absorb the CO2  and use in photosynthesis.

4. Sinks of atmospheric CO2.

Carbon sinks are the natural system that store the carbon dioxide from atmosphere.

Sinks of atmospheric CO2 are the ocean and soil.

Plants take carbon dioxide from the atmosphere to use in photosynthesis; some of this carbon is transferred to soil as plants die and decompose.

Oceans are currently largest carbon sink on Earth.