Question

How oxygen molecule formed early atmosphere?

Answer 1

Stratospheric ozone is formed naturally by chemical reactions involving solar ultraviolet radiation (sunlight) and oxygen molecules, which make up 21% of the atmosphere. In the first step, solar ultraviolet radiation breaks apart one oxygen molecule (O2) to produce two oxygen atoms (2 O) (see Figure Q2-1).

Answer 2

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The answer is tiny organisms known as cyanobacteria, or blue-green algae. These microbes conduct photosynthesis: using sunshine, water and carbon dioxide to produce carbohydrates and, yes, oxygen. ... "What it looks like is that oxygen was first produced somewhere around 2.7 billion to 2.8 billon years ago.

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