Final answer:
KOH (potassium hydroxide) is the compound that is considered a base as per the Brønsted-Lowry theory because it can accept protons, demonstrated by the formation of water from hydroxide ions and protons.
Step-by-step explanation:
In the given list of compounds, KOH (potassium hydroxide) is considered a base. This identification is based on the Brønsted-Lowry theory of acids and bases, which defines a base as a substance that can accept protons (H+ ions). KOH, when dissolved in water, dissociates into potassium ions (K+) and hydroxide ions (OH-), where the hydroxide ion can accept a proton, thus acting as a base.
For example, the net ionic equation for KOH acting as a Brønsted-Lowry base would be:
This equation shows that the OH- ion from KOH is accepting a proton to form water.
Other compounds mentioned such as HI (hydroiodic acid), HNO3 (nitric acid), and HF (hydrofluoric acid) are acids as they donate protons in aqueous solutions.