Question

which statement is not true about all the isotopes of an element? a they have the same mass number. b they have the same atomic number c they have the same number of protons. d they had different numbers of neutrons.

Explanation:

Isotopes of an element have the same atomic number (same number of protons) but different mass - numbers due to different numbers of neutrons.

Answer:

A. They have the same mass number.