Which of the following set has all the coloured ions ?

Options

A. `Cu^(+), Cu^(2+), Ni^(2+)`
B. `Cu^(2+), Co^(2+) , Sc^(3+)`
C. `Cu^(2+) , Fe^(2+) , Co^(2+)`
D. `Na^(+), Mg^(2+), Al^(3+)`

Answer

C

Explanation

In set `Cu^(2+), Fe^(2+), Co^(2+)`, all the ions have unpaired d -electrons. Hence, they are all coloured ions.
`Cu^(2+) to [Ar] 3d^9 4s^0`
`Fe^(2+) to [Ar] 3d^6 4s^0`
`Co ^(2+) to [Ar] 3d^7 4s^0`.