Colour of the compounds is due to transition of electrons.

Cyanides are not yellow.

$\begin{array}{c}{\text{BaCrO}}_4-\text{Yellow}\\ {\text{K}}_3\left[\text{Co}{\left({\text{NO}}_2\right)}_6\right]-\text{Yellow}\\ {\left({\text{NH}}_4\right)}_3\left[\text{As}\left({\text{Mo}}_3{\text{O}}_{10}\right)\right]-\text{Yellow}\end{array}$

$\mathrm{Z}{\mathrm{n}}_2\left[\mathrm{F}\mathrm{e}{\left(\mathrm{C}\mathrm{N}\right)}_6\right]$ is bluish white.