Question

does molecular oxygen have a positive charge, negative charge, or no charge?

Answer 1

I assume you mean the stable form, dioxygen (i.e., two oxygen atoms bonded to each other)? Count the number of protons and the number of electrons in the whole molecule. If there are more protons than electrons, it has a net positive charge; if it has fewer protons than electrons, it has a net negative charge. And if it has the same number of protons and electrons, it has no charge...

Answer 2

It does not have a charge! Elements in their pure form do not have charges!