Amongst `Cu^(+1), Fe ^(+2)and Cr^(+3)`
(At. No. `Cu =29, Fe =26, Cr= 24`)

Options

A. `Cu^(+1)` is colourless, `Fe ^(+2) and Cr ^(+3)` are coloured
B. all are coloured
C. all are colourless
D. only `Cr^(+3)` is coloured, `Cu^(+1) and Fe ^(+2)` are colourless

Answer

A

Explanation

`Cu^(+) ` has `d ^(10)` configuration. Hence it has no d-d tranition hence `Cu^(+)` is colourless
`Fe ^(2+)and Cr ^(3+)` have `d^(6)and d^(3)` configuration respectively. They contains unpaired electrons in d-orbitals. Hence these are coloured.