Multiple choice

The primitive atmosphere of earth was devoid of

  1. free-oxygen

  2. methane

  3. cynamide

  4. ammonia

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Earth's primitive atmosphere was reducing in nature, containing methane, ammonia, hydrogen, and water vapor but lacking free oxygen. Free oxygen only accumulated after the evolution of photosynthetic organisms billions of years later.