Which gaseous ion in its ground state has the exact same number of unpaired electrons as a neutral ground-state sulfur atom?
Fe3+\text{Fe}^{3+}Fe3+
Co2+\text{Co}^{2+}Co2+
Ni2+\text{Ni}^{2+}Ni2+
Cu2+\text{Cu}^{2+}Cu2+
