Which statement is one of the two observations supporting the hypothesis that no free molecular oxygen existed for the first 2.3 billion years after the planet formed?

+1 vote

 

Cyanobacteria did not become abundant in the oceans until 2 billion years ago.

There was no plausible source of oxygen at the time the planet cooled to solid state.

Earth rocks indicate that, for many years after the planet cooled, any oxygen that formed reacted with nitrogen in the atmosphere.

Today's volcanoes release large amounts of nitrogen, carbon dioxide, and water.

 

asked Dec 28, 2012 in Biology by anonymous
    

1 Answer

0 votes

 

There was no plausible source of oxygen at the time the planet cooled to solid state.

 

answered Dec 28, 2012 by anonymous

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