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Which of the following is responsible for permanent hardness of water ?
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- magnesium bicarbonate
- sodium chloride
- calcium sulphate
- calcium bicarbonate
- magnesium bicarbonate
Correct Option: C
Permanent hardness is caused by dissolved calcium sulfate (which is not removed by boiling). Hard water contains dissolved magnesium and calcium ions. These make it more difficult for the water to form lather with soap. Temporary hardness is caused by dissolved calcium hydrogen carbonate (which is removed by boiling)
