Which of the following gases present in air acts as an inert gas not being used by our body even though we inhale it the most?

When you breathe in, nitrogen gas will enter the blood and circulate around the body without being used up or added to. When it reaches the lungs, it will pass out again. The percentage of nitrogen inhaled is roughly 79% but it is only 74% when exhaled. Nitrogen is a rather inert gas that does not change density depending on temperature as readily as oxygen does. Nitrogen itself is not actually used up by the body. It is simply a byproduct of the nitrates and various emissions involved in photosynthesis from plants and various algae that get pumped with whimsical abandon into the atmosphere.