Question

Salts of …….causes the hardness of water

• A. $Na^{+}and \, K^{+}$
• B. $Ca^{2 +}and \, Mg^{2 +}$
• C. $Ca^{2 +}and \, K^{+}$
• D. $Ca^{2 +}and \, Na^{+}$

Answer 1

Answer: (B)

Hardness of water is due to the presence of bicarbonates, chlorides and sulphates of $Ca$ and $Mg$ on it. These $Ca^{2 +}$ and $Mg^{2 +}$ ions react with the anions of fatty acids present in soaps to form curdy white precipitates. As a result, hard water does not produce lather with soap immediately.