Question

which of the following best describes isotopes of an element?
atoms with the same number of neutrons but different numbers of protons
atoms that have the same mass number but different atomic numbers
atoms with the same number of protons but different numbers of neutrons
atoms with different numbers of protons and electrons

Explanation:

Isotopes are defined as atoms of the same element that have the same number of protons (which determines the element's identity) but different numbers of neutrons, resulting in different mass - numbers.

Answer:

Atoms with the same number of protons but different numbers of neutrons