We take all the gases that are present in the atmosphere but we breathe because oxygen is needed to burn the fuel sugars and fatty acids in our cells to produce energy. Cells do this by completely breaking down glucose (sugar) into carbon dioxide (which you breathe out). Oxygen is brought into the lungs through breathing, where it is transported by red blood cells to the entire body to be used to produce energy. Our body only needs oxygen and not nitrogen. So, the amount of nitrogen we breathe is exhaled out and not absorbed by our body unlike oxygen which our body needs.

Introduction:
Atmosphere is a mixture of various gases, including oxygen, nitrogen, hydrogen, carbon dioxide, and others. However, when it comes to taking only oxygen, we need to separate it from other gases. This process is done through various methods, such as fractional distillation, absorption, and adsorption.

Separation of Oxygen from Other Gases:
There are different methods to separate oxygen from other gases, including:

- Fractional Distillation: This method is used to separate different components of a mixture based on their boiling points. In this method, air is liquefied and then heated gradually. Different gases evaporate at different temperatures, and thus, they can be separated.

- Absorption: In this method, oxygen is absorbed by a suitable absorbent, such as zeolite, and other gases are left behind. The absorbed oxygen is then released by heating the absorbent.

- Adsorption: This method is similar to absorption, but instead of using a liquid absorbent, a solid adsorbent, such as activated carbon, is used. Oxygen is adsorbed on the surface of the adsorbent, and other gases are left behind. The adsorbed oxygen is then released by heating the adsorbent.

Why Choose Oxygen?
Oxygen is necessary for various processes, including respiration, combustion, and many industrial processes. It is also essential for the survival of many living organisms. Hence, it is widely used in various applications, including medical, industrial, and scientific.

Conclusion:
In conclusion, separating oxygen from other gases is essential for various applications. Different methods, such as fractional distillation, absorption, and adsorption, can be used for this purpose. Oxygen is chosen because of its importance and wide range of applications.