The pH of fresh groundwater slightly decreases upon exposure to air because:
2015
The pH of fresh groundwater slightly decreases upon exposure to air because:
- A.
Carbon dioxide from air is dissolved in the water.
- B.
Oxygen from air is dissolved in the water.
- C.
The dissolved carbon dioxide of the groundwater escapes into air.
- D.
The dissolved oxygen of the groundwater escapes into air.
- E.
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Correct answer: A
The pH of groundwater decreases when exposed to air because carbon dioxide dissolves in water, forming carbonic acid (H2CO3), which lowers the pH. This process is responsible for the slight decrease in pH observed upon exposure to air.