Answer to Question 1Karst develops by groundwater erosion in areas underlain by soluble rocks. Karst is usually created by
limestone. The topography is characterized by numerous caves, springs, sinkholes, solution valleys,
and disappearing streams.
Answer to Question 2Most groundwater naturally contains some carbonic acid and is slightly acidic. The water becomes
acidic when it combines with carbon dioxide (CO2) from the air or decaying organic matter. The
chemical reaction is H2O + CO2 H2CO3.