Answer:
Earth's first atmosphere 4.6 billion years ago was most likely comprised of hydrogen and helium (two most abundant gases found in the universe!)
Through the process of outgassing, the outpouring of gases from the earth's interior, many other gases were injected into the atmosphere. These include:
-water vapor (produced rain - rivers, lakes, oceans)
-carbon dioxide
-nitrogen
As outgassing occurred over a period of millions of years, the atmosphere evolved to its current state
Explanation:
