Noble gases with the highest ionisation energy and greater solubility in water are respectively

Noble gases are sparingly soluble in water and the solubility increases from helium to xenon.

Solubility of noble gases in water is due to dipole-induced dipole attractions and as the atomic size increases, the formation of induced dipole becomes easier resulting in increased solubility.

Noble Gases have a very stable electron configuration, therefore, they have the highest amount of ionization energy within their periods. It decreases down a family because electrons farther from the nucleus are easier to remove.