Which of the following statement is incorrect ?

Options

A. Nitrogen does not diffuse into blood because `pN_(2)` is same in blood and alveoli
B. Binding capacity of CO ( carbon monoxide ) is 210 times more than `O_(2)` with Hb
C. Partial pressure of `O_(2)` is more in expired air the alveolar air
D. Both 1 & 3

Answer

To determine which statement is incorrect, let's analyze each option step by step.

1. **Statement 1**: "Nitrogen does not diffuse into blood because partial pressure of nitrogen is same in blood and alveoli."
- This statement is **correct**. Diffusion of gases occurs from an area of higher partial pressure to an area of lower partial pressure. If the partial pressures are equal, there will be no net movement of nitrogen into the blood.

2. **Statement 2**: "Binding capacity of carbon monoxide is 210 times more than oxygen with hemoglobin."
- This statement is also **correct**. Carbon monoxide binds to hemoglobin with a much higher affinity than oxygen, making it 210 times more effective at binding to hemoglobin than oxygen.

3. **Statement 3**: "Partial pressure of the oxygen is more in expired air than the alveolar air."
- This statement is **incorrect**. The partial pressure of oxygen in expired air is actually lower than that in alveolar air. This is because expired air contains a mixture of fresh air and air that has already participated in gas exchange, which has a lower oxygen concentration.

4. **Statement 4**: "Both first and third."
- This statement is **incorrect** because while the first statement is correct, the third statement is incorrect.

**Conclusion**: The incorrect statement is **Statement 3**.