Question

We frequently measure the oxygen content in chemical reactions involving combustion or respiration. Since oxygen is needed for these processes, it is frequently obtained from the atmosphere, which contains around 21

1) carbon dioxide
2) nitrogen
3) oxygen
4) water vapor

Answer 1

The oxygen content in chemical reactions involving combustion or respiration is obtained from the atmosphere, which contains around 21% oxygen. Oxygen is necessary for combustion and is used by living things for respiration. The other main gases in the atmosphere are nitrogen, carbon dioxide, and water vapor.

Step-by-step explanation:

The oxygen content in chemical reactions involving combustion or respiration is frequently obtained from the atmosphere, which contains around 21 oxygen. Oxygen is essential for combustion processes such as the burning of fuels and is used by all living things for respiration and aerobic respiration. The main gases in the atmosphere, besides oxygen, are nitrogen, which is the most common gas, carbon dioxide, and water vapor.