Which of the following ion is expected to be colourless? — Atomic Structure Chemistry Question

💡 Solution & Explanation

A colourless ion generally lacks unpaired d-electrons to undergo d-d transitions. Zn$^{2+}$ has a $3d^{10}$ configuration (fully filled d-orbitals) and is therefore colourless. The others have partially filled d-orbitals. Therefore, correct answer is C.