passwella.
Menu

JAMB Chemistry 2010 Question 13

Question 13

Water

Permanent hardness of water can be removed by

  1. A.filtration
  2. B.adding slaked lime
  3. C.adding caustic soda
  4. D.boiling
Show the answer and explanation

Answer: C (adding caustic soda)

Explanation

Permanent hardness (CaSO4, MgSO4) is not removed by boiling or by slaked lime; it needs a chemical that precipitates the Ca2+ and Mg2+ ions, such as washing soda or caustic soda.