When did the level of oxygen in earth's atmosphere become high enough to sustain aerobic respiration? when did the level of oxygen in earth's atmosphere become high enough to sustain aerobic respiration? 3.5 billion years ago 1.5 billion years ago 2.7 billion years ago 1.0 billion years ago

2.4 billion years ago

Explanation:

The formation of the tertiary atmosphere, with the re-arrangements of the plates, took  that influenced the long term evolution of the planet that transferred the carbon dioxide to the large continental stores and the surplus oxygen came into formation about 2.4 billion years ago during the massive oxygenation event that leads to the appearance at the end of the banded iron formations.  The process of photosynthesis also added and reduced the material that reduces the oxidation of the atmosphere and kept ion place till 15% of the Precambrian period had ended.

They are all solids.

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