Which acid is commonly responsible for the dissolution of limestone (CaCO_3) in natural environments?

• A. Nitric acid (HNO_3)
• B. Sulfuric acid (H_2SO_4)
• C. Carbonic acid (H_2CO_3)
• D. Hydrochloric acid (HCl)

Answer: (C)

Verified step by step guidance

1. Understand that limestone is primarily composed of calcium carbonate (CaCO_3), which reacts with acids to dissolve.
2. Recognize that in natural environments, the acid responsible for dissolving limestone is typically formed from carbon dioxide (CO_2) dissolving in water, creating carbonic acid (H_2CO_3).
3. Recall the chemical reaction where carbonic acid reacts with calcium carbonate: \(\mathrm{CaCO_3 + H_2CO_3 \rightarrow Ca^{2+} + 2HCO_3^-}\), which leads to the dissolution of limestone.
4. Note that while other acids like nitric acid (HNO_3), sulfuric acid (H_2SO_4), and hydrochloric acid (HCl) can dissolve limestone, they are not commonly present in natural environments in significant amounts.
5. Conclude that carbonic acid (H_2CO_3) is the acid most commonly responsible for limestone dissolution in nature due to its formation from atmospheric CO_2 and rainwater.