Question

........... is lost while breathing out during exercise.

• A. No loss
• B. Health
• C. Energy
• D. Water

Answer 1

The correct option is D Water

Water is lost by the body either through the skin or by respiration (moist air exhaled). Through the skin, about 400ml of water is lost per day. Every day, we breathe in about 14000L of air. Assuming that the humidity of exhaled air is 100% and the inhaled air is 20%, and using the carrying capacity of 1kg of air to be 20g of water vapour, we can calculate how much water is lost simply by breathing. This estimate gives 400ml of water lost per day too. Thus, a person loses about 800ml of water per day, half through the skin and half through respiration. When we exercise and our muscles work harder, our body uses more oxygen and produces more carbon dioxide. To cope with this extra demand, breathing has to increase from about 15 times a minute (12 litres of air) when at rest, up to about 40–60 times a minute (100 litres of air) during exercise. Hence, the amount of water lost while breathing out increases during exercise.

So, the correct answer is 'Water'.