A. 5
B. 5-6
C. 8.7-10.5
D. 6.5-8.5
Explanation:
The pH of pure water (H20) is 7 at 25 °C, but when exposed to the carbon dioxide in the atmosphere this equilibrium results in a pH of approximately 5.2 because CO2 in the air dissolves in the water and forms carbonic acid.