Answer:
heavier gases - sank to the surface
lighter gases - escaped into space
oxygen - produced through photosynthesis
carbon dioxide - released by volcanoes
Explanation:
Since the formation of the atmosphere on Earth, there has been constant changes in it, gradually leading to the atmosphere that we have nowadays. In the distant past, the atmosphere was much different, and it took lot of time for it to become what it is. The volcanoes with their activity contributed to constant release of carbon dioxide, resulting in the greenhouse effect. The organisms that are able to perform photosynthesis started to release lot of oxygen into the atmosphere, thus setting up better living conditions. The gravity of our planet contributed to the vertical distribution of the gasses, with the heavier being lower, and the lighter ones being further up or released into space.
