Statement I: HF is thermally most stable hydrogen halide.
Statement II:  ${\mathrm{O}}_2{\mathrm{F}}_2$ is used in the removal of plutonium as ${\mathrm{PuF}}_6$ from spent nuclear fuel.

(1)The thermal stability of these halides decreases down the group, due to decrease in bond (H-X) dissociation enthalpy.

Thus, HF> HCl > HBr > HI

(2)Pu+3O₂​F₂​$\to$PuF₆​+3O₂​ ; unreacted Pu is separated by fluorination.

Both statements are correct