Isotopes of an element have: the same physical properties. same chemical properties. different number of neutrons. different atomic numbers.

The correct options are same chemical properties. different number of neutrons. Isotopes: Any of two or more forms of a chemical element, having the same number of protons in the nucleus, or the same atomic number, but having different numbers of neutrons in the nucleus, or different atomic weights. Isotopes show different physical properties but same chemical properties.