2
The first shell contains 2 electrons, and the outer shell (or the valence shell) contains 6 electrons.
Oxygen has 2 electrons in the innermost orbital and 6 in the outermost (valence) orbital.
Because "orbital shell" is a confusing term to me (several orbitals, also called sub-shells, exist within each energy level), I will cover several aspects of oxygen's electrons in fear of not...
on the innermost shell of any element there is 2 electrons (except for Hydrogen, but that's a different story) so the answer would be 2
It has six
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