Which ion could bond with a calcium ion (Ca^{2+}) to form a neutral ionic compound?

• A. NO_3^{-}
• B. SO_4^{2-}
• C. 2 Cl^{-}
• D. PO_4^{3-}

Answer: (C)

Verified step by step guidance

1. Identify the charge on the calcium ion, which is given as \(\mathrm{Ca^{2+}}\), meaning it has a +2 charge.
2. To form a neutral ionic compound, the total positive charge must balance the total negative charge from the anion(s).
3. Examine each ion option and its charge: \(\mathrm{NO_3^{-}}\) has a -1 charge, \(\mathrm{SO_4^{2-}}\) has a -2 charge, \(\mathrm{Cl^{-}}\) has a -1 charge, and \(\mathrm{PO_4^{3-}}\) has a -3 charge.
4. Determine how many of each anion would be needed to balance the +2 charge of calcium: one \(\mathrm{SO_4^{2-}}\) ion balances one \(\mathrm{Ca^{2+}}\) ion; two \(\mathrm{Cl^{-}}\) ions are needed to balance one \(\mathrm{Ca^{2+}}\) ion; one \(\mathrm{NO_3^{-}}\) ion would not balance the charge alone; \(\mathrm{PO_4^{3-}}\) cannot balance the +2 charge with a single ion.
5. Conclude which ion or combination of ions can bond with \(\mathrm{Ca^{2+}}\) to form a neutral compound by matching total positive and negative charges.