Among `TiF_(6)^(2-), CoF_(6)^(3-), Cu_(2)Cl_(2)" and "NiCl_(4)^(2-)` the colourless species are :

Options

A. `CpF_(6)^(3-) and NiCl_(4)^(2-)`
B. `TiF_(6)^(2-) and CoF_(6)^(3-)`
C. `NiCl_(4)^(3-) and Cu_(2)Cl_(2)`
D. `TiF_(6)^(2+) and Cu_(2)Cl_(2)`

Explanation

`Ti^(4+),[Ar]^(11)3d^(0)4s^(0)`, as there is no unpaired electron, so so d-d transition occurs.
`Cu^(+),[Ar]^(31)3d^(10)4s^(0)` , All electrons paired, so there is no aspaired electron for d-d transition.
Hence both complexes are colourless.