People will choke, hyperventilate and die
21%
No. Oxygen is not believed to have been present in the early years of Earth's history.
The Earth
no
Earth
phytoplankton :)
Oxygen composes of twenty-one percent of Earth's Atmosphere.
Oxygen is believed not to be present at the time of Earth's formation.
The term omnipresent means to be present at all times. Based on that definition, no, oxygen is not always present on the Earth even though oxygen is a key element to our existence.
Oxygen.
Oxygen
Earth