Which pair of compounds is expected to show similar colour in aqueous medium?

Options

A. `FeCl_(3) and CuCl_(2)`
B. `VOCl_(2) and CuCl_(2)`
C. `COCl_(2) and FeCl_(2)`
D. `FeCl_(2) and MnCl_(2)`

Answer

B

Explanation

Colour of transition metal ion salt is due to d-d transition of unpaired electrons of d-orbital.Metal ion salt having similar colour in aqueous medium.In `VOCl_(2)`, vanadium is present as `V^(4+)` and in `CuCl_(2)`, copper is present as `Cu^(2+)`
So`._(23)V=1s^(2),2s^(2)2p^(6),3s^(2),3d^(3),3p^(6),3d^(3),4s^(2) `
`V^(4+)=1s^(2),2s^(2),2p^(6),3s^(2),3p^(6),3d^(1)`

Number of unpaired electron=1
and `._(29)Cu=1s^(2),2s^(2),2p^(6),3s^(2),3p^(6),3d^(10),4s^(1)`
`Cu^(2+)=1s^(2),2s^(2),2p^(6),3s^(2),3p^(6),3d^(9)`

Number of unpaired electron=1
Hence, `VOCl_(2)` and `CuCl_(2)` show similar colour.