Four statements about two different isotopes of the same element are listed. Which statement must be correct?
They have different numbers of protons.
They have different chemical properties.
They have different numbers of neutrons.
They have different numbers of electrons in their neutral atoms.
284 exam-style questions on CIE IGCSE Physics 5.1 The nuclear model of the atom, covering 5.1.1a Structure of the atom and ions, 5.1.1b Alpha-particle scattering, 5.1.2a Composition of the nucleus and isotopes, 5.1.2b Proton number, nucleon number and nuclide notation, and 5.1.2c Nuclear fission and nuclear fusion. Each one has a worked solution and a mark scheme showing where the marks go.