which feature of the ammonia molecule leads to the formation of the ammonium ion when ammonia dissolves in water .name the other ion formed when ammonia dissolves in water.

When ammonia dissolves in water following reaction takes place:-

 NH₃ + H₂O ---------> NH₄⁺ + OH^-

Here ammonia is a base which abstract the proton from the water molecule which leads to the formation of ammonium ion. Other ion is hydroxyl ion.