For the Arrhenius concept, acid is a substance that, in water, produces the hydrogen ion (H⁺), and base in the substance that, in water, produces the hydroxyl ion (OH⁻).
For the first reaction then KOH must produce OH⁻ so its a base, and HNO₃ must produce H⁺ so it's an acid.
For the second one, HI must produce H⁺ so it's an acid. For the concept of Arrhenius, (CH₃)₃N can't be classified as a base or as an acid.
