Question

Which of these was the first source of oxygen in our atmosphere



Oxygen produced by living things on land


Oxygen released by volcanoes


Oxygen released by living cyanobacteria in the ocean which then was released into the atmosphere


the original accretion of the Earth

Answer 1

@GIitter @Yinshy

Answer 2

Oxygen released by living cyanobacteria in the ocean which then was released into the atmosphere

Answer 3

can u answer 1 more

Answer 4

sure

Answer 5

What caused dissolved iron to rust and deposit in banded iron formations?



outgassing


oxygen released by living cyanobacteria


huge amounts of rain


an asteroid impact

Answer 6

i think its b but im not sure

Answer 7

i gotta go

Answer 8

okay ?

Answer 9

first source of oxygen

I'd have to go for the original earth formation. - we got lucky ?

Answer 10

The key to this question is cyanobacteria. In calm, shallow marine environments the iron which was present in seawater combined with the oxygen that was released from the photosynthesis that the cyanobacteria performed. This occurred due to large amounts of oxygen that was present in the early atmosphere, so the excess bonded with iron. so it will be oxygen released by living cyanobacteria

Answer 11

where did the "oxygen released" by the bacteria come from in the first place ? Only what was already in the earth on formation ????
I'd go for the last one on that basis.
Esp if there were no nuclear reactions which might "play alchemist", so to speak, with the elements.
The bio stuff is biochemical, and that implies rearranging pre existing atoms. And the q seems to be asking "where did those atoms come from in the first place" and the answer to that, to me, is the accretion thing.
Mind you, I could be wrong.