Question

1. today, carbon dioxide is a part of the oxygen - cycle that keeps all forms of life alive. why was carbon dioxide an important gas in earths early atmosphere?

Explanation:

In Earth's early atmosphere, carbon - dioxide was important as a greenhouse gas. It trapped heat, keeping the planet warm enough for the development of life. It also played a role in chemical reactions that contributed to the formation of other substances necessary for life processes.

Answer:

It helped keep the planet warm and was involved in key chemical processes for life - relevant substances formation.