Which of the following statements is not true of the isotopes of an element? They
Answer Details
The statement that is not true of the isotopes of an element is "have the same mass number". Isotopes are atoms of the same element that have the same atomic number (same number of protons in the nucleus), but a different mass number (different number of neutrons in the nucleus). Therefore, isotopes have the same chemical properties, since chemical properties are determined by the number and arrangement of electrons in the atom, which is determined by the atomic number. However, because isotopes have a different number of neutrons, they may have slightly different physical properties, such as different atomic masses, densities, and radioactive properties.