Statement I : Zeolites are used as ion exchangers and molecular sieves.
Statement II : Zeolites consist cavities of different sizes and can trap Ca⁺² ions from hard water and also molecules like NH₃, CO₂ etc.

(1) Sodium Zeolite is used to remove permanent hardness of water(used as water softner).

the formula of Zeolite is Na₂Al₂Si₂O₈ .xH₂O (or) simply NaAlSiO₄ (or) NaZ

Which is Known as Sodium Aluminium silicate

(2) In sheet silicates , one-fourth or one-half of Silicon ions are replaced by Al⁺³ ions , then Zeolite  formed

They trap Ca⁺² ions from hard water and replace Na⁺  ions, hence acts as ion exchanger.

2NaZ_(s) + M⁺² _(aq.) $\to$MZ_{2 (s)} + 2Na⁺   _(aq.)  [ M = Mg , Ca ]

(3) The structure of Zeolite permits the formation of cavities of different sizes.

Molecules like Water, NH₃ , CO₂and ethanol are trapped in these cavities.

Hence Zeolites acts as molecular sieves