What is the chemical formula for strontium peroxide?

Strontium peroxide is composed of strontium cations (Sr^2+) and peroxide anions (O2^2-). Strontium typically has a +2 oxidation state, which is why we denote the cation as Sr^2+. The peroxide anion, on the other hand, contains two oxygen atoms that are bonded and carries a -2 charge overall.

To achieve a neutral compound, one strontium cation (with a +2 charge) will combine with one peroxide anion (with a -2 charge) to balance the charges. This results in the formula SrO2, indicating that one strontium atom is paired with two oxygen atoms from the peroxide group. Therefore, the correct chemical formula for strontium peroxide is indeed SrO2.

Understanding the charges and how they balance each other is key to deducing the correct formula in ionic compounds, particularly those containing polyatomic ions like peroxides. The other choices do not represent the correct combination of strontium and the peroxide ion, resulting in unbalanced formulas or incorrect oxidation states.