For `Zn^(2), Ni^(2+), Cu^(2+) and Cr^(2+)` which of the following statements is correct ?

Options

A. Only `Zn^(2+)` is colourless and `Ni^(2+) and Cr^(2+)` are coloured.
B. All the ions are coloured.
C. All the ions are colourless.
D. `Zn^(2+) and Cu^(2+)` are colourless while `Ni^(2+) and Cr^(2+)` are coloured

Answer

A

Explanation

`Zn^(2+)(3d^10)` has zero unpaired electrons (coloured).
`Ni^(2+)(3d^8)` has 2 unpaired electrons (coloured).
`Cu^(2+)(3d^9)` has 1 unpaired electrons (coloured).
`Cr^(2+)(3d^4)` has 4 unpaired electrons (coloured).