Oxygen is a pure element. It's element 8 on the Periodic Table. 8 protons, 8 electrons, 8 neutrons. Atomic Mass is about 16 amu (atomic mass units)
not your business
Yes
No, it is not.
helium
gas
20.94 % in our atmosphere.
No, it is an element.
Hemoglobin.....
oxgyen
It needs it to breathe.
capillary
Through the blood stream