Question

formation of O2 molecule

Answer 1

A molecule that is composed of two oxygen atoms, O2, that has no color, odor, or taste. It is present in both the atmosphere and the oceans, and solar radiation with wavelengths less then 242 nm can break it back into oxygen atoms, O2 ---> O + O. One of these oxygen radicals in turn can combine with O2 to form ozone, O2 + O ---> O3.
that's your answer

Answer 2

Oxygen has 2 valence electrons . so when it combines with another oxygen molecule it forms covalent bond by sharing the electrons in the last shell(4)to complete its octet and achieve an inert state.So thus it forms O=O

which is nothing but O2.

hope it helps