(a) What is ventilation perfusion ratio?

Explanation

Ventilation Perfusion Ratio : It is the ratio of the volume of alveolar ventilation in one minute to the volume of cardiac output at the same time.
The volume of alveolar ventilation and the cardiac output per minute are 4 litres and 5 litres respectively.
So, Ventilation Perfusion Ration `("4 litre")/("5 litre")=0.8`