Earth first atmosphere was mostly likely created by

(4.6 billion years ago)

As Earth cooled, an atmosphere formed mainly from gases spewed from volcanoes. It included hydrogen sulfide, methane, and ten to 200 times as much carbon dioxide as today's atmosphere. After about half a billion years, Earth's surface cooled and solidified enough for water to collect on it.

Explanation:

Just formed Earth: Like Earth, the hydrogen (H2) and helium (He) were very warm. Hope this helps. Please mark as brainliest.

answer; researchers typically cannot control people's sexual behaviors as would be necessary in an experiment;

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