The chemicals used to soften hard water involves the addition of?

A. insoluble sodium compounds which form soluble solutions of calcium and magnesium
B. soluble sodium compounds which form soluble solutions of calcium and magnesium ions
C. soluble sodium compounds which form insoluble precipitates of calcium and magnesium ions
D. insoluble precipitates of calcium and magnesium ions

Correct Answer:

Option C – soluble sodium compounds which form insoluble precipitates of calcium and magnesium ions