What is the difference between an atom in the ground state and an atom in an excited state? a. the atom in the ground state has less energy and is less stable than the atom in an excited state. b. the atom in an excited state has one fewer electron than the atom in the ground state. c. the atom in an excited state has more energy and is less stable than the atom in the ground state. d. the atom in an excited state has one more electron than the atom in the ground state.