Q4. Assertion: CO diffuses readily from blood into the alveoli although its partial pressure gradient is small. Reason: the solubility of CO is 20–25 times higher than that of O. Are both true, and does the reason explain the assertion?
Both are true, and the reason explains the assertion (NCERT page 188).
Q5. What is partial pressure?
The pressure contributed by an individual gas in a mixture of gases, written pO for oxygen and pCO for carbon dioxide (NCERT page 187).
Q6. Besides the pressure gradient, which two factors affect the rate of diffusion of gases?
The solubility of the gases and the thickness of the membranes involved in diffusion (NCERT page 187).
Q7. By how many mm Hg does the pO fall from atmospheric air to the alveoli?
159 − 104 = 55 mm Hg (NCERT Table 14.1, page 187).