The question is incomplete, the complete question is shown in the image attached.
The ion that is not isoelectronic with the noble gas neon is O^2+.
To be "isoelectronic" means to have the same number of electrons. When we say that a specie is isoelectronic with the noble gas neon, we mean that the specie has 10 electrons just as neon does.
All the ions listed in the options have 10 electrons except O^2+ which has six electrons.
Therefore, the ion that is not isoelectronic with the noble gas neon is O^2+.
Learn more: https://brainly.com/question/2094768
