Multiple choice general knowledge science & technology Isotopes of an element contain the same number of protons but different number of neutrons the same number of neutrons but different number of protons equal number of protons and electrons equal number of nucleons Reveal answer Fill a bubble to check yourself A Correct answer Explanation Isotopes are atoms of the same element with identical atomic numbers (same protons) but different mass numbers (different neutrons). This variation in neutrons changes atomic mass while preserving chemical identity.