Which of the following metal salts is responsible for permanent hardness in water?

Explanation

Dissolved calcium chloride supplies calcium ions and contributes to permanent, or noncarbonate, hardness. Ordinary boiling does not remove it as it removes bicarbonate hardness. Calcium hydrogencarbonate is associated with temporary hardness; sodium chloride and potassium chloride do not supply the usual hardness-producing calcium or magnesium ions.