Chlorides and sulphates of _______________( sodium and magnesium/ calcium and magnesium) cause permanent hardness.

• The water that does not form lather with soap is called hard water.
• The hardness of water is caused due to the dissolved chlorides, sulphates, and bicarbonates of calcium and magnesium.
• Permanent hardness is caused by the chlorides and sulphates of calcium and magnesium.

Hence, chlorides and sulphates of calcium and magnesium cause permanent hardness.