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JAMB Chemistry 2004 Question 15

Question 15

Water

Hardness of water is caused by the presence of the ions of

  1. A.magnesium and silver
  2. B.calcium and magnesium
  3. C.sodium and potassium
  4. D.calcium and sodium
Show the answer and explanation

Answer: B (calcium and magnesium)

Explanation

Dissolved Ca2+ and Mg2+ ions react with soap to form scum, which is what makes water hard.