Question

The element “O₂” on the datasheet is molecular oxygen, meaning two oxygen atoms bonded together by sharing their outer electrons. These microscopic molecular structures can only exist where temperatures are much lower than the 5800 K of the Sun’s photosphere. (At such high temperatures, collisions between atoms and molecules and photons would break O₂’s weak bonds and obliterate the molecule). Therefore, the line produced by O₂ absorption does not come from O­₂ in the Sun. Where do you expect to find molecular oxygen in amounts large enough to create a deep, prominent solar spectral line? (As a hint, you also find a lot of molecular nitrogen at this location).

Answer 1

in molecular form, O2 has a double bond, which has a lower bond dissociation energy than the triple bond in molecular nitrogen
hence
the triple bond needs more bond dissociation energy to be dissociated into elemental nitrogen
hence
at 5800K the molecular oxygen cant exist byt molecular nitrogen can becuase of more stability of triple bond and hence we can say that the sun's photosphere has molecular nitrogen

now, the absorption spectrum of oxygen and nitrogen molecular, overlap, due to which the line which we thought was due to molecular oxygen absorption line is actiually molecular nitrogen absorption line