The scale formation in a kinetic used for boiling water is caused by the presence in water of?

  • A calcium sulphate
  • B calcium carbonate
  • C calcium hydrogen carbonate
  • D calcium hydroxide
  • E magnesium sulphate
jamb 1981chemistry

The correct answer is C. calcium hydrogen carbonate

The scale is produced when soluble Ca(HCO3)2 breaks down on heating to form insoluble CaCO3

eqn Ca (HCO3)2(aq) -----> CaCO3 (s) + CO2 (g) + H2O (l)

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