An abundance of ______ was conspicuously absent from the Earth’s atmosphere 4 billion years ago.

Question

KollegeApply · Accepted Answer

An abundance of free oxygen was conspicuously absent from the Earth’s atmosphere 4 billion years ago. Explanation: The early Earth’s atmosphere was reducing, containing gases like hydrogen, nitrogen, carbon dioxide, methane, and ammonia, but it lacked free oxygen. Free oxygen started accumulating only later, after the evolution of photosynthetic aerobic organisms.

AChoose Your Answer