JEE Main · 2022 · 29 Jul 2022 · Shift 1 · d and f Block Elements

Transition metal ions are colored when they have partially filled d-orbitals that allow d-d electronic transitions. ${\mathrm{Sc}}^{3+}$ has $3d^0$ configuration and ${\mathrm{Zn}}^{2+}$ has $3d^{10}$ configuration—both have no unpaired d-electrons and cannot undergo d-d transitions, making them colorless. All other options contain at least one ion with partially filled d-orbitals (${\mathrm{Cu}}^{2+}:3d^9$, ${\mathrm{V}}^{2+}:3d^3$, ${\mathrm{Ti}}^{3+}:3d^1$, ${\mathrm{Mn}}^{2+}:3d^5$), which are colored.