Question

permanent hardness of water cannot be cured by

Answer 1

Water hardness is of two types (1) temporary hardness is caused by dissolved calcium bicarbonate (Ca(HCO3)2) and can be cured by boiling or by adding calcium hydroxide or lime (Ca(OH)2) to water; (2) permanent hardness is caused by dissolved calcium sulphate (CaSO4) and cannot be curedby boiling,but by certain.

Answer 2

Answer:Boiling

Explanation:other three are use to convert hard water to soft water in terms of permanent hardness