Question

Which of the following pair of ions are responsible for the hardness of water?

• A. $C{a}^{2+}$ and $A{l}^{3+}$
• B. $N^{+}$ and $A{l}^{3+}$
• C. $M{g}^{2+}$ and $C{a}^{2+}$
• D. $B{e}^{2+}$ and $N{a}^{3+}$

Answer 1

The correct option is C $M{g}^{2+}$ and $C{a}^{2+}$

Calcium and magnesium salts in the form of hydrogen carbonates, chlorides and sulphates are responsible for the hardness of water.
Hence, the correct answer is option (c).