So, kevinkevin:, you have two choices for each of the two ions -- acid or base for each. Now, the old saw goes, a salt of a weak base and a strong acid give a weakly acidic solution. Now, can you use the Ka's of each ion, like Raderford: said, to determine what each is, a strong acid, and a weak base? I'd heard that nitric acid is a strong acid and ammonium hydroxide is a weak base, but since you've come to these problems right about now, it would be better if you can use the Ka to prove it.