The scale formation in a kinetic used for boiling water is caused by the presence in water of?
calcium sulphate
calcium carbonate
calcium hydrogen carbonate
calcium hydroxide
magnesium sulphate
Correct answer is C
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)