The table shows three nuclei.
| Nucleus | Atomic number | Mass number |
|---|---|---|
| P | 18 | 40 |
| Q | 19 | 40 |
| R | 18 | 38 |
Which identifies an isotope pair and the nucleus with the greatest number of neutrons?
Isotope pair P and R; greatest neutron number P
Isotope pair P and R; greatest neutron number Q
Isotope pair P and Q; greatest neutron number P
Isotope pair Q and R; greatest neutron number R
103 exam-style questions on Edexcel GCSE Physics 6.1 Atomic structure and isotopes, covering 6.1.1 Structure of the atom, 6.1.2 Isotopes: atomic and mass number, 6.1.3 Sub-atomic particles: masses and charges, and 6.1.4 Electron orbits and energy changes. Each one has a worked solution and a mark scheme showing where the marks go.