Question

List the various steps involved in inhalation and exhalation

Answer 1

You must be knowing that air moves from high pressure region to low pressure region.
when you inhale, diaphragm contracts pushing down lungs increasing the space in lungs. So as air is abundant outside, it moves to low pressure region i.e lungs. 
This is just opposite while exhaling; where diaphragm relaxes so also the lungs decreasing space , pushing the extra air out.

Answer 2

air is abundant outside, it moves to low pressure region i.e lungs. This is just opposite while exhaling; where diaphragm relaxes so also the lungs decreasing space , pushing the extra air out.