Which of the following can never be isoelectronic species?

Question

which of the following can never be isoelectronic species?

a. anions of 2 different elements

b. cations of 2 diff elements

c. an anion and a cation

d. an anion and an atom

e. atoms of 2 diff elements

what is an isoelectronic species?

please help..

Answer 1

An isoelectronic series is a group of ions and/or atoms that have an equal number of electrons.

e. atom of 2 different elements can never have the same number of electrons because they have different numbers of protons. In neutral atoms, the number of electrons equals the number of protons.