When an ionic solute is added to water, it causes a phenomenon known as boiling point elevation. This means the presence of the solute will increase the boiling point of the water above its normal boiling point, which is 100°C at standard atmospheric pressure.
Given the options:
- 115°C
- 86°C
- 121°C
- 106°C
The boiling point that is not reasonable after adding an ionic solute is 86°C, because this temperature is below the normal boiling point of pure water. Adding a solute would not decrease the boiling point; therefore, 86°C is not a reasonable boiling point for the solution. The other temperatures are all higher than 100°C and could be reasonable boiling points for the solution, depending on the amount and type of solute added.