Final answer:
In the reaction between potassium hydroxide and carbonic acid, potassium ions are present in the complete ionic equation, while water (H2O) does not dissociate and is therefore not represented by individual ions.
Step-by-step explanation:
When solutions of carbonic acid and potassium hydroxide react, compounds that are not present in the complete ionic equation are typically those that remain unchanged during the reaction; these are called spectator ions. However, in the scenario described, carbonic acid is not a strong electrolyte, so it won't completely dissociate into ions. Therefore, carbonic acid itself will not appear fully as separate ions in the complete ionic equation.
However, potassium ions (K+) and water (H2O) are actually products of the reaction, as exemplified by the given reaction: 2KOH + CO2 → K2CO3 + H2O. In a complete ionic equation, potassium would appear as potassium ions, and water will not be dissociated into ions and will remain as H2O. Therefore, potassium ion is indeed present in the complete ionic equation, while water will not dissociate.