Question

Hard water contains dissolved salts of______ and _______.

Options

• sodium, potassium

• sodium, magnesium

• calcium, magnesium

• calcium, potassium

Answer 1

Hard water contains dissolved salts of calcium and magnesium.

Explanation:

Hard water is water that contains high concentrations of Ca²⁺ and Mg²⁺ ions, typically in the form of their bicarbonates, sulphates, and chlorides (e.g., CaCO₃, MgSO₄, CaCl₂). These ions react with soap to form insoluble curdy precipitates (scum), which reduces soap's lathering ability and makes it ineffective for washing.