The radii of F,F−,O and O−2 are in the order of
O2->F->O>F
O2->F->F>O
F->O2->F>O
O2->O>F->F
Atomic radius decreases on going from left to right in a period. Thus size of O>F. As O2− and F− are isoelectronic, therefore, size of O2−>F−
The radii of F,F−,O and O2− are in the order of