Out of $\mathrm{TiF}_6^{2-}$ and $\mathrm{CoF}_6^{3-}, \mathrm{Cu}_2 \mathrm{Cl}_2$ and…
Out of $\mathrm{TiF}_6^{2-}$ and $\mathrm{CoF}_6^{3-}, \mathrm{Cu}_2 \mathrm{Cl}_2$ and $\mathrm{NiCl}_4^{2-}$ ( $\mathrm{Z}$ of $\mathrm{Ti}=22, \mathrm{Co}=27, \mathrm{Cu}=29, \mathrm{Ni}=28)$ the colourless species are :
$\mathrm{CoF}_6^{3-}$ and $\mathrm{NiCl}_4^{2-}$
$\mathrm{TiF}_6^{2-}$ and $\mathrm{CoF}_6^{3-}$
$\mathrm{Cu}_2 \mathrm{Cl}_2$ and $\mathrm{NiCl}_4^{2-}$
$\mathrm{TiF}_6^{2-}$ and $\mathrm{Cu}_2 \mathrm{Cl}_2$
Solution
In both $\mathrm{TiF}_6^{2-}$ and $\mathrm{Cu}_2 \mathrm{Cl}_2$, these no $\mathrm{d}-$ electrons or no unpaired electrons so, these are colourless.