What happens when carbon dioxide levels in the blood decrease to below normal? A. pH of the blood decreases. B. the blood becomes more acidic. C. the concentration of hydrogen ions in the blood decreases. D. pH does not change.
Option C. Carbon dioxide reacts with water to shape carbonic acid and thence hydronium ions. So a lower in CO 2 will lower the concentration of hydro- nium ions (and pH will increase).