Which of the following statements is/are correct

Zeolites are 3D silicates in which some of the $Si{O}_4^{4-}$ units are replaced by $A\mathcal{l}{O}_4^{5-}$ ions. Due to honey comb structure they can take up small molecules.  
The sodium ions present in zeolites are exchanged with cations like $M{g}^{2+}$ or $C{a}^{2+}$ during the softening of hard water.