Question

how to separate naphthalene and ammonium chloride by sublimation

Answer 1

Nahthalene is highly insoluble in water while ammonium chloride is not.

We can add distilled water to the mixture to dissolve the ammonium chloride and then recover the ammonium chloride by evaporation; the naphthalene will not dissolve in water in any substantial quantity, therefore you can separate naphthalene from ammonium chloride.