Which statement about elements in the d-block of Period 4 of the periodic table is correct?
A copper(I) ion (Cu+\text{Cu}^{+}Cu+) has the electronic configuration 1s22s22p63s23p63d94s11\text{s}^2 2\text{s}^2 2\text{p}^6 3\text{s}^2 3\text{p}^6 3\text{d}^9 4\text{s}^11s22s22p63s23p63d94s1.
A titanium(III) ion (Ti3+\text{Ti}^{3+}Ti3+) has three unpaired electrons in its 3d sub-shell.
A cobalt(II) ion (Co2+\text{Co}^{2+}Co2+) has exactly three unpaired electrons in its d-orbitals.
Both scandium (Sc\text{Sc}Sc) and zinc (Zn\text{Zn}Zn) are transition elements because they are located in the d-block of Period 4.
