JAMB - Chemistry (2014 - No. 11)
Water is said to be temporarily hard when it contains
Ca (HCO3)2 and Mg (HCO3)2 salts
Ca (HCO3)2 and CaCO3 SALTS
Mg(HCO3)2 and CaSO4 salts
CaSO4 and Ca(HCO3)2 salts
Explication
Temporary hardness is caused by the presence of dissolved calcium hydrogentrioxocarbonate(IV) and magnesium hydrogentrioxocarbonate(IV) which decomposes on heating to form calcium trioxocarbonate(IV) and magnesium trioxocarbonate(IV) respectively.