Chapter 3 - Exercises - Page 150b: 55

See the explanation

The three ions that are isoelectronic with neon are: a) $F^-$ b) $O^{2-}$ c) $N^{3-}$ These ions have the same electron configuration as neon (1s^2 2s^2 2p^6), but they have different nuclear charges, which affects their size. The order of these ions from smallest to largest is: $F^- < O^{2-}