Water is said to be permanently hard when it contains:

Correct answer: D. chlorides of Ca2+ and Mg2+ ions

  • A. carbonates of Ca2+ and Mg2+ ions
  • B. Bicarbonates of Ca2+ and Mg2+ ions
  • C. sulphates of Na+ and Mg2+ ions
  • D. chlorides of Ca2+ and Mg2+ ions

Explanation

The presence of soluble salts of calcium and magnesium, i.e., sulfates and chlorides of calcium and magnesium, causes permanent hardness in the water.

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