Concept:Stalactites and stalagmites are cave formations made when dissolved minerals are deposited inside limestone caverns.
Explanation:Rainwater mixes with carbon dioxide from the air and forms a weak carbonic acid solution.
This acidic water reacts with calcium carbonate in limestone rock, converting it into soluble calcium bicarbonate.
The chemical change can be shown as:
CaCO3+H2O+CO2→Ca(HCO3)2As this solution drips through cracks into underground caves, it loses carbon dioxide gas.
Calcium carbonate is then deposited once again from the solution.
Drips that lose
CO2 while hanging from the roof form downward-growing stalactites.
Drops that fall to the cave floor build upward-growing stalagmites.
This process only takes place in limestone areas, not in granite, sandstone, or basalt regions.
Answer:C. Limestone