Question

Identify the correct statements regarding breathing.

• A. The percentage of carbon dioxide in exhaled air is 0.04%.
• B. The percentage of oxygen in inhaled air is 16.4%.
• C. The breathing rate is the number of breaths in one minute.
• D. Normal breathing rate of an adult human is 15-18 times a minute.

Answer 1

Answer: (C), (D)

Normal breathing rate of an adult human is 15-18 times a minute.

$\bullet$ The percentage of carbon dioxide in exhaled air is 4.4% and in inhaled air is 0.04% (as present in the atmosphere).

$\bullet$ The percentage of oxygen in the inhaled air is the percentage of oxygen present in the atmosphere i.e., 21%. The percentage of oxygen in the exhaled air is 16.4%.

$\bullet$ The number of times a person breathes is termed as breathing rate. It is 15-18 times/min of an adult in resting state. During excercise it increases to 25 times/min.