J. J. Thomson, who discovered the electron in 1897, proposed the plum pudding model of the atom in 1904 before the discovery of the atomic nucleus in order to include the electron in the atomic model. In Thomson's model, the atom is composed of electrons (which Thomson still called “corpuscles,” though G. J.
Zinc Oxide is the IUPAC name for ZnO
The answer is B because isotopes have the same number of protons and neutrons.
