Final answer:
J.J. Thompson's model theory, also known as the plum pudding model, was partially successful in explaining the structure of an atom but was eventually replaced by more accurate models.
Step-by-step explanation:
J.J. Thompson's model theory, also known as the plum pudding model, was an early model proposed to explain the structure of an atom. According to Thompson's model, the atom consists of a positively charged sphere with negatively charged electrons embedded in it, much like plums in a pudding.
The success of Thompson's model was limited. It was later replaced by the Rutherford model, which introduced the idea of a dense nucleus at the center of the atom. The Rutherford model was further refined into the Bohr model and eventually led to the modern understanding of the atom.
Therefore, the state of success of J.J. Thompson's model theory can be considered as c. Partially successful. While it provided some insights into the structure of the atom, it was unable to fully explain experimental observations and was eventually replaced by more accurate models.