Multiple choice

The two metal ions that cause hardness to water are

  1. Sodium, Magnesium

  2. Calcium, Magnesium

  3. Sodium, Calcium

  4. Sodium, Potassium

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Hard water is caused by the presence of minerals mainly calcium and magnesium in it. The minerals get into the water if it passes through soft rocks like chalk or limestone. If water passes through hard rocks like granite or through peaty soils, it does not pick up these minerals therefore remains soft.

 

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