The hardness of water is due to the presence of which of the following ions?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Ca2+ and Mg2+
Water is called hard when it contains dissolved calcium and magnesium salts (hydrogencarbonates, chlorides and sulphates). These Ca2+ and Mg2+ ions react with soap to form an insoluble scum, so soap does not lather well.