Correct Response: D. The scattering of the alpha particles that were used to bombard a thin sheet of gold foil demonstrated the existence of a small, dense, positively charged atomic nucleus. Although Rutherford did develop the concept of half-life of a radioactive element (A), the alpha-scattering experiments did not contribute to the development of that concept. Creation of new radioactive isotopes by nuclear bombardment (B) is incorrect because Rutherford's alpha-scattering experiments had nothing to do with creating new isotopes. Changing one atomic element into another through nuclear reactions (C) is incorrect because Rutherford's alpha-scattering experiments had nothing to do with changing one atomic element into another.
