The nucleus was discovered by James Chadwick in an experiment involving the bombardment of the nucleus of which atom with α-particles? 

The nucleus was discovered by James Chadwick in an experiment involving the bombardment of the nucleus of the Beryllium atom with α-particles. Chadwick carried the experiments,using many different elements as radiadtion targets besides paraffin, what really occured when one bombarded beryllium with alpha particles, there was the formation of a carbon-12 nucleus and the emission of a neutron.