Xenon trioxide

a. Preparation of Xenon trioxide ($\mathrm{XeO_3}$) : Fluorides of xenon react with water to form $\mathrm{XeO_3}$.

The first of these hydrolyses is a disproportionation: part of the xenon is reduced to the element while part is oxidised from the +4 to the +6 state in $\mathrm{XeO_3}$ — which is why elemental xenon and oxygen appear alongside the trioxide. In the second, $\mathrm{XeF_6}$ (already +6) exchanges all six fluorines for three oxygens without any change in oxidation state. The book writ …