Question

how the distribution of nucleons in nuclei is detetmined​

Answer 1

$\underline{\underline{\sf{Answer}}} \:$

⟹The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment.

⟹ Almost all of the mass of an atom is located in the nucleus, with a very small contribution from the electron cloud.