The element expected to form largest ion to achieve the nearest noble gas configuration is:

To reach Neon configuration:$\text{N}$ gains 3 electrons $\to {\text{N}}^{3-}$$\text{O}$ gains 2 electrons $\to {\text{O}}^{2-}$$\text{F}$ gains 1 electron $\to {\text{F}}^{-}$$\text{Na}$ loses 1 electron $\to {\text{Na}}^{+}$ These are isoelectronic species (all have 10 electrons). In isoelectronic species, the ion with the lowest nuclear charge ($Z$) will have the largest radius because the nucleus exerts less pull on the same number of electrons.Atomic numbers: $\text{N}(7),\text{O}(8),\text{F}(9),\text{Na}(11)$.${\text{N}}^{3-}$ has the smallest $Z$, so it is the largest ion.