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.
This question appeared on the ETEA MDCAT 2011 paper, which you can sit online with every answer explained.
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