Which of the following set has all the coloured ions ?

Options

A. `Cu^(+), Cu^(2+), Ni^(2+)`
B. `Cu^(2+), Ca^(2+), Sc^(2+)`
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 th 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).`