1. Which gas is most abundant in the air we breathe in?

2. Which component in the air we breathe is essential for the survival of life?

3. What is the percentage of oxygen in inhaled air?

4. What is the percentage of carbon dioxide in exhaled air?

5. The main organ in the human respiratory system?

6. The muscular sheet-like structure found below the lungs?

7. In which direction does the diaphragm move during inhalation?

8. What are the tiny air sacs inside the lungs called?

9. Which part of the skeletal system protects the lungs?

10. What happens to the ribs during exhalation?