ANATOMY

Detailed explanation-1: -The amount of inhaled air contains 21% oxygen and 0.04% carbon dioxide, while the air we breathe out contains 16.4% of oxygen and 4.4% of carbon dioxide. This is because our cells use oxygen from the inhaled air to release energy and give out carbon dioxide and water vapour.

Detailed explanation-2: -Three vital respiratory gases-oxygen (O(2)), nitric oxide (NO), and carbon dioxide (CO(2))-intersect at the level of the human red blood cell (RBC).

Detailed explanation-3: -Carbon dioxide is the waste product of the body that needs to be expelled out through exhalation. It is saturated with water vapours, that’s why water vapours also come out with it. So the correct answer is ‘Exhaled air’.

Detailed explanation-4: -Breathing. Every day an average person breathes in around 14, 000 litres of air, and with every breath, we release a small amount of water vapour. Over a day, this builds up to around 400g of water vapour created. People who are active will breathe out more due to higher internal temperatures.