Final answer:
The compound CAS does not correspond to the ions in the provided options. Instead, the compounds formed from the pairs of ions mentioned would be calcium oxide (CaO) for calcium and oxygen, copper(II) sulfide (CuS) for 2+ copper and sulfur, and copper(I) sulfide (Cu2S) for 1+ copper and sulfur.
Step-by-step explanation:
The compound CAS seems to be a typo or a misrepresentation of a compound's formula. However, to address the options provided for identifying ions, none match the 'CAS' notation. Instead, let us resolve the ions present in the given options. For the compound Calcium and Sulfur, the ions would be the calcium cation (Ca2+) and the sulfide anion (S2-). For a Copper and Silver compound, these would form cations, however, they are not commonly paired in a simple ionic compound. For Chlorine and Sodium, these would be the chloride anion (Cl-) and the sodium cation (Na+), respectively, which combine to form sodium chloride (NaCl), a common table salt.
Given the context provided from exercises and solutions, here are the correct formulas for ionic compounds composed of the pairs of ions mentioned:
- The compound composed of the calcium ion and the oxygen ion would be calcium oxide (CaO).
- For the 2+ copper ion and the sulfur ion, the compound would be copper(II) sulfide (CuS).
- And finally, for the 1+ copper ion and the sulfur ion, the correct formula would be copper(I) sulfide (Cu2S) due to copper's 1+ oxidation state requiring two copper ions for every sulfur ion to balance the charges.