Before there was any life on earth, which gas was absent from earth’s ancient atmosphere?

Which is an example of a decomposer? a. bear b.algae c.grass d.bacteria d bacteria

Ateam from new york presbyterian hospital is conducting a study about a recent increase in cases involving both excess sweating and kidney stones. what would the team need before it draws a conclusion about the cases? medications that are specifically designed to treat the sickness machines that are built to process blood and reduce symptoms until patients are healthy again data that profile the various patients who report these symptoms proof that the excess sweating is related to the excessive kidney stones

What are some natural processes that represent physical and chemical changes?