Answer to Question 1
ANS: C
The KA is small because the H2CO3 concentration is quite large with respect to the numerator of reaction (3). The value of KA is always the same for H2CO3 at equilibrium, regardless of the ini-tial concentration of H2CO3. A strong acid, such as HCl, has a large KA because the denominator HCl is extremely small, compared with the numerator (H+ Cl).
Answer to Question 2
ANS: D
Isohydric buffering and ventilation are the two major mechanisms responsible for maintaining a stable pH in the face of massive CO2 production.