Question

While respiration only oxygen is used where do other gases do?

Answer 1

During respiration we inhale only the oxygen and exhale other gases, which again mix with the atmospheric gases.

Answer 2

During respiration, we inhale all the atmospheric gases but as soon as the oxygen is absorbed to the body, the other gases which are of no use to us are given back to the atmosphere through exhaling. We exhale co2 at a higher rate (co2 of environment and co2 realesed by our body)