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
170 exam-style questions on CIE IGCSE Physics 5.1.2a Composition of the nucleus and isotopes. Each one has a worked solution and a mark scheme showing where the marks go.