Question

If the following ion(s) is/are coloured enter 1, else enter 0.

$Z{n}^{2+}$

Answer 1

$Z{n}^{2+}$ ion is colourless. Its configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{10}$.

In order to absorb visible light, an electron would have to move to a higher energy orbital . The difference in energy of the orbitals would have to equal the energy of a visible wavelength photon.

For d orbital splitting, the energy difference is right for the visible range. Unfortunately for $d^{10}$ ions, the orbitals are full. The next empty orbital that an electron could move into is much higher in energy, and would correspond to UV light. And therefore they are colourless.