Question

If O2 is lighter than O3, why O3 is not found in ground surface?

Answer 1

I guess because its unstable therefore it reacts instantaneously with organic and inorganic molecules through its third oxygen atom by oxidation.

Answer 2

^Exaclty. O3 is a highly unstable compound and gets easily reduced by compounds like CFCs. This is the reason of the so called "Ozone Depletion"

Answer 3

Good job guys, it was like a common sense question but question is a question.
@ArvindG & @Abmon98

Answer 4

You are welcome!

Answer 5

Because Ozone formation needs UV radiation which is not readily available near earth surface.

Answer 6

I was thinking too that maybe O3 is more unstable