Which solution has the highest boiling point 1.0 m kno3

2.0 M Ca(NO3)2

First off, the greater the charge on your ions, the stronger the ion-dipole forces are between the ions and water molecules in solution. Ca2+ has a greater charge than K+. Also, the more concentrated the solution, the more ions you have, and therefore more ion-dipole forces overall. The stronger the intermolecular forces are, the higher the boiling point.