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Question

Scientists have inferred that Earth's ORIGINAL atmosphere was formed by the...

1) outgassing from Earth's interior

2) erosion of Earth's surface

3) decay of microorganisms in Earth's oceans

4)radioactive decay of elements in Earth's oceans

Answer 1

Water and the atmosphere was created by outgassing from Earth's interior through volcanoes and cracks in the surface.  Water then allowed cyanobacteria (blue-green algae) to form, the first living organism on the planet, about 2.8 billion years ago.  This allowed oxygenation of the newly formed atmosphere, since they produce oxygen.

(cyanobacteria are still thriving today btw)

Answer 2

1) outgassing from Earth's interior

The Earth's atmosphere was formed by planetary degassing, a process in which gases like carbon dioxide, water vapor, sulphur dioxide and nitrogen were released from the interior of the Earth from volcanoes and other processes. Life forms on Earth have modified the composition of the atmosphere since their evolution.