The correct statement is:
**A solution of potassium hydroxide will always have more OH⁻ ions than a solution of ammonia.**
### Explanation:
- **Conductivity**: Potassium hydroxide (KOH) is a strong base and dissociates completely in solution, producing a high concentration of OH⁻ ions, which contributes to high conductivity. Ammonia (NH₃) is a weak base and does not dissociate completely, resulting in lower conductivity.
- **Concentration of Solute**: The concentration of solute cannot be determined solely based on the nature of the base (strong vs. weak) without specific concentrations being mentioned.
- **pH**: KOH generally has a higher pH than ammonia due to its complete dissociation; however, the exact pH comparison will depend on the concentrations of each solution.
- **OH⁻ Ions**: KOH will always produce a greater quantity of OH⁻ ions in solution when compared to ammonia for equal concentrations because KOH fully dissociates while ammonia only partially dissociates and produces OH⁻ through a different equilibrium reaction.
Thus, the statement regarding the number of OH⁻ ions is the most universally correct.