Question

Why aqueous ammonia solution is considered a base although ammonia does not contain hydroxyl ion?

Answer 1

Ammonia itself obviously doesn't contain hydroxide ions, but it reacts with water to produce ammonium ions and hydroxide ions. So as it yields hydroxyl ions ,It is considered basic.
hope it helps:)

Answer 2

Answer:ammonia dissolve in water as follows :

Explanation the hydroxy ions produced in the solution are responsible for basic character of ammonia.