Question

Among `TiF_(6)^(2-), CoF_(6)^(3-), Cu_(2)C1_(2)` and `NiC1_(4)^(2-)` (At. No. `Ti = 22, Co = 27, Cu = 29, Ni = 28)`, the colourless species are -
A. `Cu_(2)CI_(2)` and `NiCI_(4)^(2-)`
B. `TiF_(6)^(2-)` and `Cu_(2)CI_(2)`
C. `CoF_(6)^(3-)` and `NiCI_(4)^(2-)`
D. `TiF_(6)^(2-)` and `CoF_(6)^(3-)`

Answer 1

Correct Answer - B
Colourless species are those which have either `d^(0)` or `d^(10)` configuration so that d-d transitions are ruled out.
`Cu_(2) CI_(2) implies Cu^(+) (d^(10)), NiCI_(4)^(2-) implies Ni^(2+) (d^(8))`
`TiF_(6)^(2-) implies Ti^(4+) (d^(0)), CoF_(6)^(3-) implies (3d^(6))`