Among the given items, first and second substance causes temporary hardness in water. There are two types of water hardness: temporary and permanent hardness. Temporary hardness: due to the presence of calcium hydrogen carbonate Ca(HCO3)2(aq) and magnesium hydrogen carbonate Mg(HCO3)2(aq) Permanent hardness: due to thepresence of the chlorides, nitrates and sulphates of calcium and magnesium. Temporary hardness can be removed by boiling the water but permanent hardness cannot be removed by boiling.