The balanced chemical equation for the removal of sulphate hardness, using a zeolite softener, is:
a. MgZ + 2NaCl = Na2 + MgCl2
b. Ca(HCO3)2 + Na2Z = CaZ + 2NaHCO3
c. CaZ + 2NaCl = Na2Z + CaCl2
d. MgSO4 + Na2Z = MgZ + Na2SO4
e. MgSO4 + Na2Z = 2MgZ + 2NaSO4
Answer: D