Question

What is the % of oxygen in inhaled air and exhaled air?

• A. 0.3 and 4.4
• B. 21 and 16
• C. 78 and 78
• D. 100 and 2

Hint:

Air composition:
• Oxygen in inhaled air \( \approx 21\% \)
• Oxygen in exhaled air \( \approx 16\% \)

Answer 1

The Correct Option is B

Concept:
Atmospheric air contains several gases. Major components:
• Nitrogen \( \approx 78\% \)
• Oxygen \( \approx 21\% \)
• Carbon dioxide \( \approx 0.04\% \) During breathing:
• Oxygen is absorbed by lungs
• Carbon dioxide is released Thus: \[ \text{Inhaled air contains } 21\% \text{ oxygen} \] and \[ \text{Exhaled air contains } 16\% \text{ oxygen} \]

Step 1: Understand inhalation and exhalation.
Inhalation:
• Oxygen-rich air enters lungs Exhalation:
• Carbon dioxide-rich air leaves lungs

Step 2: Understand oxygen exchange.
Inside alveoli:
• Oxygen diffuses into blood
• Carbon dioxide diffuses out Hence oxygen percentage decreases in exhaled air.

Step 3: Analyze all options carefully.
Option (A): 0.3 and 4.4
These values relate more closely to carbon dioxide percentages. Incorrect. Option (B): 21 and 16
Correct oxygen percentages. Correct. Option (C): 78 and 78
Represents nitrogen percentage. Incorrect. Option (D): 100 and 2
Incorrect values. Incorrect.

Step 4: Choose the correct answer.
Therefore, oxygen percentage in inhaled and exhaled air is: \[ \boxed{21 \text{ and } 16} \] Hence, \[ \boxed{(2)\ 21 \text{ and } 16} \]