The diagram above shows which phenomenon of respiration?

Which muscles undergo contraction during normal expiration?

Arrange the given steps by which the lungs show inspiration,in the sequence of events occurring first:
$I.$ Increase in the volume of the thoracic chamber in the dorsoventral axis
$II.$ Upward and outward movement of the ribs
$III.$ Contraction of intercostal muscles
$IV.$ Entry of air inside the lungs
$V.$ Contraction of the diaphragm
$VI.$ Increase in the volume of the thoracic chamber in the anteroposterior axis
Choose the correct option.

Select the correct events that occur during inspiration.
$(a)$ Contraction of diaphragm
$(b)$ Contraction of external inter-costal muscles
$(c)$ Pulmonary volume decreases
$(d)$ Intra pulmonary pressure increases

Lungs do not collapse between breaths and some air always remains in the lungs which can never be expelled because

Lung ventilation movements are due to