A particular nuclide of potassium can be represented by the symbol shown:
1939K ^{39}_{19}\text{K} 1939KHow many neutrons are there in a neutral atom of this nuclide?
19
20
39
58
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.