Ammonia can be dried Using

A basic substance must be dried using a basic drying agent.If an acidic drying agent is used it reacts with the substanceNH3 is basic. It can not dried using conc. H2SO4 (or) P2O5 which are acidicdue to the salt formationNH3 + H2SO4 (NH4)2SO4NH3+P2O5 ( NH4 )3PO4NH3 can not be dried using anhydrous CaCl2 because it forms Co-ordinate covalent bondsThus the best drying agent to remove moisture from NH3 is CaO(quick lime)