Question

Which have different numbers of electrons?

different ions of an element
different isotopes of an element
the nucleus of an element
each of the atoms of an element

Answer 1

Answer: different ions of an element.

Why:
- Different ions of the same element have lost or gained electrons, so their electron counts differ (e.g., Na has 11 e−, Na+ has 10 e−).
- Different isotopes of an element have different numbers of neutrons but the same number of protons — neutral isotopes therefore have the same number of electrons.
- The nucleus contains protons and neutrons, not electrons.
- Neutral atoms of a given element all have the same number of electrons equal to the element’s atomic number.