Which of the following is the correct molecular formula for calcium carbonate?

• A. CaCO_2
• B. Ca_2CO_3
• C. CaCO_3
• D. Ca_2(CO_3)_2

Answer: (C)

Verified step by step guidance

1. Identify the ions involved in calcium carbonate: calcium ion (Ca^{2+}) and carbonate ion (CO_3^{2-}).
2. Recall that calcium has a charge of +2 and carbonate has a charge of -2, so they combine in a 1:1 ratio to balance the charges.
3. Write the formula by combining one calcium ion with one carbonate ion, resulting in CaCO_3.
4. Check the options given and compare them to the correct formula CaCO_3 to see which matches the correct ratio and composition.
5. Confirm that CaCO_3 is the correct molecular formula because it reflects the proper stoichiometric balance of calcium and carbonate ions.