None of the above cations are isoelectronic with krypton.
Atoms and ions with the same amount of electrons, same electronic structure and same number of valence electrons are said to be isoelectronic species. Or, an isoelectronic pair is a pair of species with the same amount of electrons that combines all the atoms of a certain species. The radii of isoelectronic species would vary due to varying nuclear charges. Here Krypton has 36 electrons and all of the cations mentioned have 18 electrons in total.
Learn more about isoelectronic species:
brainly.in/question/118329
#SPJ4
