Question

Where does the oxygen that keep us alive comes from?

Answer 1

The oxygen which is required to keep a person alive is produced by plants during the process of photosynthesis in plants.

In which plants take CO2(carbon dioxide) and H2O (water) as raw material and converts it into C6H12O6(glucose) and O2 (oxygen) in the presence of sunlight and chlorophyll.

Answer 2

Almost all the oxygen you breathe comes from green plants. They produce oxygen during a process called photosynthesis. During photosynthesis green plants manufacture the sugar molecules fructose and glucose. Green plants use energy from sunlight to build sugar molecules from carbon dioxide and water.