WAEC Chemistry 2019 Paper

Concept:Atoms with the same mass number can have the same number of neutrons when their proton numbers differ by the same amount.Explanation:For $^{64}_{29}\mathrm{Cu}$, the mass number is $64$ and the proton number is $29$.Number of neutrons $= 64 - 29 = 35$.For $^{65}_{30}\mathrm{Zn}$, the mass number is $65$ and the proton number is $30$.Number of neutrons $= 65 - 30 = 35$.Therefore, both atoms have the same number of neutrons.They do not have the same number of protons, electrons, or nucleons.Answer:C. neutrons