Hardness of water is caused by the presence of

ASolid particles in the water

BPathogens in the water

CToxic metals in the water

DCations in the water ✓ Correct

Correct answer: (D) Cations in the water

Explanation

Water hardness is caused by dissolved cations, chiefly calcium and magnesium ions.

Suspended solid particles cause turbidity, not the hardness of water.

Pathogens in water make it unsafe to drink but do not create hardness.

Toxic metals pose a health hazard yet are not the general cause of hardness.

These calcium and magnesium ions react with soap and hinder its lathering.

Hardness is often expressed as an equivalent concentration of calcium carbonate.

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