Final answer:
Karst topography is a landscape formed in limestone regions characterized by features like sinkholes and caves, created by the dissolution of limestone by acidic groundwater over thousands of years.
Step-by-step explanation:
The terrain feature associated with limestone regions characterized by sinkholes, sinks, and sinking streams is known as karst topography. This landscape is formed when areas with limestone bedrock undergo dissolution from acidic groundwater. Limestone, primarily consisting of the mineral calcite (CaCO3), is susceptible to erosion and dissolution in the presence of carbonic acid, which forms when rainwater mixes with carbon dioxide from the atmosphere.
Features such as sinkholes and caves result from the dissolution of limestone over thousands of years. Sinkholes are depressions or holes that occur when the surface layer collapses into the caverns below. Water from rain or melting glaciers reacts with carbon dioxide to form carbonic acid, which slowly erodes the limestone and enlarges underground caverns, leading to the formation of impressive structures such as stalactites and stalagmites.
Equations from chemistry illustrate how solubility equilibria and pH levels play crucial roles in karst formation. As an example, the reverse process of the equation CaCO3 + CO2 + H2O ↔ Ca2+ + 2HCO3- demonstrates the dissolution of limestone in acidic conditions which contributes to karst features.