Hard water is high in calcium and magnesium ions. Soft water is typically high in which of the following ions?

• A. Sodium ions (Na^+)
• B. Chloride ions (Cl^-)
• C. Potassium ions (K^+)
• D. Iron ions (Fe^{2+})

Answer: (A)

Verified step by step guidance

1. Understand the difference between hard water and soft water. Hard water contains high concentrations of calcium (Ca^{2+}) and magnesium (Mg^{2+}) ions, which cause water hardness.
2. Soft water, on the other hand, has low concentrations of calcium and magnesium ions. It often contains higher concentrations of other ions that do not cause hardness.
3. Identify common ions that replace calcium and magnesium in soft water. Sodium ions (Na^{+}) are typically used in water softening processes because they do not contribute to hardness.
4. Recognize that chloride ions (Cl^{-}) and potassium ions (K^{+}) may be present but are not the primary ions associated with soft water characteristics.
5. Conclude that sodium ions (Na^{+}) are the typical ions found in soft water, as they replace calcium and magnesium ions during the softening process.