Question

whyozon lies higher lavel even its mass is havier than oxygen. ​

Answer 1

Ozone doesn't really remain, anywhere. It has a short lifetime - about an hour. There is more ozone at higher altitudes not because it is remaining there but because new ozone is continually being produced as older ozone reacts and becomes something else.

In the stratosphere, ozone is quite easily produced. An oxygen molecule is struck by a photon of ultraviolet light, splitting the molecule into two oxygen atoms. Each of these atoms can then bond with an oxygen molecule, forming two ozone molecules (O3).