Which statement about a sodium nucleus represented by 1123Na^{23}_{11}\text{Na}1123Na is correct?
It contains 11 neutrons.
It contains 11 electrons.
It contains 11 protons.
It contains 12 nucleons.
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.