The order ${\mathrm{Mg}}^{+2}>{\mathrm{Na}}^{+}>{\mathrm{F}}^{-}$of ionic radius is not correct.
These are isoelectronic species and each species contains 10 electrons. The correct order of ionic radii is ${\mathrm{Mg}}^{+2}>{\mathrm{Na}}^{+}>{\mathrm{F}}^{-}$. The effective nuclear charge decreases in the order ${\mathrm{Mg}}^{+2}>{\mathrm{Na}}^{+}>{\mathrm{F}}^{-}$. Hence, the ionic radii increase in the order ${\mathrm{Mg}}^{+2}>{\mathrm{Na}}^{+}>{\mathrm{F}}^{-}$