The amount of air exhaled from lungs as water vapour is about:

Correct option is C

Ans. (c)
Sol. The human body loses water in various ways, including respiration, sweating, urination, and feces. During breathing, water vapour is exhaled along with carbon dioxide. The average amount of water lost through exhalation is approximately 400–600 mL per day, with an average of about 1000 mL (1 liter) in normal conditions. This amount can increase with physical activity, fever, or dry air.
Explanation of each option:
· (a) 100 ml – Incorrect. This is too low; water loss via exhalation is significantly higher.
· (b) 500 ml – Incorrect. While within the range, the average is closer to 1000 mL/day.
· (c) 1000 ml – Correct. On average, humans exhale about 1 liter (1000 mL) of water vapour per day.
· (d) 1500 ml – Incorrect. This value is above the normal range, though it may occur in extreme conditions like heavy exercise.
Thus, the correct answer is (c) 1000 ml, as this is the average amount of water exhaled from the lungs as vapour per day.