Chemistry - Hydrogen and Its compound Question with Solution | TestHub

The incorrect statements are A, B, and D.

A. Permanent hardness is caused by chlorides and sulfates of Ca²⁺ and Mg²⁺. Bicarbonates cause temporary hardness.

B. Temporary hardness is caused by bicarbonates of Ca²⁺ and Mg²⁺.

D. Calgon's method uses sodium hexametaphosphate ($\mathrm{N}{\mathrm{a}}_6{\mathrm{P}}_6{\mathrm{O}}_{18}$) to sequester $\mathrm{C}{\mathrm{a}}^{2+}$ and $\mathrm{M}{\mathrm{g}}^{2+}$ ions, not form a precipitate.