Question

The most common

Answer 1

Answer:

One theory suggests that the early atmosphere came from intense volcanic activity, which released gases that made the early atmosphere very similar to the atmospheres of Mars and Venus today. These atmospheres have: a large amount of carbon dioxide. little or no oxygen.

The early atmosphere was probably mostly carbon dioxide, with little or no oxygen. There were smaller proportions of water vapour, ammonia and methane. As the Earth cooled down, most of the water vapour condensed and formed the oceans.

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Answer 2

Answer:

There were smaller proportions of water vapour, ammonia, and methane.

Explanation:

The early atmosphere was probably mostly carbon dioxide, with little or no oxygen. As the Earth cooled down, most of the water vapour condensed and formed the oceans.