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^(+1)` is colourless as it has no unpaired electron `(3d^10 4s^0) ,Fe^(+2)` is coloured as it has one unpaired electron `(3d^4 4s^0), Cr^(+3)` is coloured as it has three unpaired electron `(3d^3 4s^0)`