Question

The salts of ________ do not cause hardness of water.

• A. sodium
• B. magnesium
• C. potassium
• D. both $A$ and $C$

Answer 1

Answer: (D)

both $A$ and $C$

Hard water is the water that contains soluble salts of bivalent ions like calcium and magnesium principally in the form of bicarbonates, chlorides, and sulfates. Monovalent ions donot cause hardness of water.

Sodium and potassium being monovalent ions donot cause hardness of water.

option D is correct