Ans. The structure of an atom was discovered through various experiments, most notably by Ernest Rutherford's gold foil experiment in 1911. This experiment involved firing alpha particles at a thin sheet of gold foil. Rutherford observed that some alpha particles were deflected, suggesting the presence of a dense, positively charged nucleus at the center of the atom. This experiment led to the development of the nuclear model of the atom, which forms the basis of our understanding of atomic structure.