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

• A. Ca_3(CO_3)_2
• B. Ca_2CO_3
• C. CaCO_3
• D. Ca(CO_2)_3

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. Determine the charges of each ion: calcium ion has a charge of +2, and carbonate ion has a charge of -2.
3. Balance the charges so that the total positive charge equals the total negative charge, resulting in a neutral compound.
4. Since both ions have charges of magnitude 2 but opposite signs, they combine in a 1:1 ratio to form CaCO_3.
5. Verify the formula by checking that the total charge sums to zero: (+2) + (-2) = 0, confirming CaCO_3 is the correct formula.