Question

What is O2 and O3?

Answer 1

Well, these are oxygen molecules........or oxygen allotropes........

Explanation:

`O_2` is the oxygen you are breathing now, and comprises some `20.95%` of the atmosphere..........

..........under exceptional circumstances, oxygen can exist as the ozone molecule, `O_3`, a bent molecule whose Lewis structure we would represent as `""^(-)O-O^(+)=O`. This site reports that ozone comprises `"0.6 ppm"` of the atmosphere.