Cobalt has a mass number of 59 and an atomic number of 27
The mass number of an atom is equal to the sum of the number of protons and neutrons in its nucleus. In this case, cobalt has a mass number of 59. This means that it has a total of 59 protons and neutrons in its nucleus.
The atomic number of an atom represents the number of protons in its nucleus. Cobalt has an atomic number of 27, which means that it has 27 protons in its nucleus.
Since protons and neutrons have approximately the same mass (1 atomic mass unit), we can infer that cobalt has 32 neutrons (59 - 27 = 32).