It is generally believed that the following gas was missing in the primordial atmosphere: A) H₂ B) CO₂ C) CH₄ D) NH₃ E) O₂

Question

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Oxygen (O₂) was missing in the primordial atmosphere of Earth. The early atmosphere was reducing, composed mainly of nitrogen, carbon dioxide, and inert gases, but lacked free oxygen. Oxygen began to accumulate in the atmosphere with the advent of photosynthetic organisms.

It Is Generally Believed That the Following Gas Was Missing