The correct answer is option 3 - They are isoelectronic with each other.

Let`s break down each option to better understand why option 3 is correct:

Option 1 states that 20Ne, 23Na+, 19F-, and 24Mg2+ are isomers of each other. Isomers are compounds with the same molecular formula but different arrangements of atoms. However, the given entities are not compounds but rather atomic or ionic species. Therefore, option 1 is incorrect.

Option 2 suggests that 20Ne, 23Na+, 19F-, and 24Mg2+ are isotopes of each other. Isotopes are atoms of the same element with different numbers of neutrons. However, the given entities do not belong to the same element. Therefore, option 2 is incorrect.

Option 3 correctly states that 20Ne, 23Na+, 19F-, and 24Mg2+ are isoelectronic with each other. This means that they have the same number of electrons and thus share similar electron configurations. This similarity in electronic configuration can be attributed to their position in the periodic table and their similar reactivity patterns. Therefore, option 3 is the correct answer.

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