Question

What scientists discovered that the nucleus contains neutrons in addition to protons?

Answer 1

James Chadwick

Explanation:

In 1920, Ernest Rutherford postulated that there were neutral, massive particles in the nucleus of atoms. This conclusion arose from the disparity between an element's atomic number (protons = electrons) and its atomic mass (usually in excess of the mass of the known protons present). James Chadwick was assigned the task of tracking down evidence of Rutherford's tightly bound "proton-electron pair" or neutron.

In 1930 it was discovered that Beryllium, when bombarded by alpha particles, emitted a very energetic stream of radiation.

In 1932, Chadwick proposed that this particle was Rutherford's neutron.