do we just breathe with oxygen or oxygen is mix with other gases.

the air we breathe is about 80% nitrogen.

We primarily breathe in a mixture of gases, of which oxygen is the most important component. The air we inhale is made up of approximately 78% nitrogen, 21% oxygen, and small amounts of other gases such as carbon dioxide, argon, and trace gases. Oxygen is vital for our survival as it plays a critical role in the process of cellular respiration, enabling our bodies to produce energy.

If you are wondering how we know the composition of Earth's atmosphere, it comes from the field of atmospheric science, which involves studying the properties and behavior of the Earth's atmosphere. Scientists have developed various techniques to measure the concentration of gases in the atmosphere, such as using gas analyzers, satellite observations, and air sampling techniques. These measurements provide us with accurate information about the relative proportions of gases in the air we breathe.