Question

Why there is always some residual volume of air in lungs after every expiration?

Answer 1

Residual volume helps us in the case of emergency. As in if the oxygen supply stops or slows down, the residual oxygen is transported to all the cells.

Answer 2

$\huge\mathfrak\red{Heya\:Mate}$

$\huge{\boxed{\bold{ANSWER}}}$

During the breathing cycle, when air is taken in and let out, the lungs always contain a residual volume of air so that there is sufficient time for oxygen to be absorbed and for the carbondioxide to be released.

$\large{\bold{HOPE \:IT \:HELPS \:YOU!!!}}$