Question

Which of the following ions will cause hardness in water sample?

• A. $C{a}^{2+}$
• B. $N{a}^{+}$
• C. $C{l}^{-}$
• D. $K^{+}$

Answer 1

Answer: (A)

Presence of calcium and magnesium salts in the form of hydrogencarbonate, chloride and sulphate in water makes water ‘hard’.