Which hypothesis of thomson's atomic model was later found to be not true by rutherford and why?

Thomson described the atom using the "plum pudding" model, wherein there is uniform distribution of protons and electrons throughout the atom.  

Rutherford tested the plum pudding model by executing the "gold foil" experiment. Rutherford that most of the alpha particles went right through the gold foil, which was in according to the plum pudding model.  However, he noticed that a few alpha particles rebounded almost directly backwards.

This was the critical observation which caused Rutherford to discard Thomson’s atomic model and he reasoned that most of the mass in an atom was concentrated in a nucleus. Rutherford thus established the planetary model of the atom, in which all positively charged protons resided in the nucleus and the electrons orbited around the nucleus like planets around the sun.

the potential energy of the reactants is 200j.

from the energy diagram, the energy of the product formed is 350j; this means that, this reaction is an endothermic reaction, because it absorbs energy from its environment.