Final answer:
Prior to the gold foil experiment, Rutherford believed in the plum pudding model, which depicted the atom as a ball of positive charge with electrons inside. His experiment's results led to the discovery of the nucleus and the rejection of the plum pudding model.
Step-by-step explanation:
Before the gold foil experiment, Rutherford believed in the plum pudding model of the atom, which was proposed by his mentor J. J. Thomson. This early atomic model depicted the atom as a spherical ball of positive charge with negatively charged electrons scattered within similar to plums in a pudding.
However, the unexpected deflection of alpha particles during his experiment led Rutherford to conclude that the atom had a very small and dense core, now known as the nucleus, resulting in the development of the nuclear model of the atom.
Rutherford believed in the plum pudding model of the atom before conducting the gold foil experiment. The plum pudding model suggested that the atom was a spherical ball of positive charge, with negatively charged electrons scattered throughout.
However, Rutherford's experiment showed that some alpha particles were deflected, indicating the presence of a small and dense nucleus at the center of the atom. Therefore, the correct answer is C) Spherical with a dense nucleus.