Chemistry - PERIODIC TABLE Question with Solution | TestHub

For isoelectronic species ionic radii decreases as the charge on ion decreases. Further on moving down in a group ionic radii increases. Hence the correct order is ${\mathrm{O}}^{2-}<{\mathrm{N}}^{3-}<{\mathrm{S}}^{2-}<{\mathrm{P}}^{3-}$