Question

what is the role of trachea and
residual volume of air ​

Answer 1

In other words, it is the volume of air that cannot be expelled from the lungs. This volume remains unchanged regardless of the lung volume at which expiration was started. ... The residual volume is an important component of the total lung capacity (TLC) and the functional residual capacity (FRC).

Answer 2

Residual volume (RV) is the volume of air remaining in the lungs after strenuous exhalation when the lungs feel completely empty. Residual volume prevents the broncheoli and the alveoli from sticking together. Residual volume is approximately 1.5 liters (adults).

The trachea – the tube connecting the throat to the bronchi.

hope it helped;-)