Hardness of water is mainly due to the presence of?

A. calcium hydroxide or magnesium hydroxide
B. calcium trioxocarbonate (IV) or calcium tetraoxosulphate (VI)
C. sodium hydroxide or magnesium hydroxide
D. calcium chloride or sodium chloride salts

Correct Answer:

Option B = calcium trioxocarbonate (IV) or calcium tetraoxosulphate (VI)

Explanation

Salts of Calcium and Magnesium are responsible for hardness of water. Bicarbonates, Carbonates, Chlorides, and Sulfates of Calcium and Magnesium cause temporary and permanent hardness.