Question

Which of the following pair is expected to exhibit the same colour in solution?

• A. $VOC{l}_2,ZnS{O}_4$
• B. $MnC{l}_2,ZnS{O}_4$
• C. $CuC{l}_2,HgC{l}_2$
• D. $CuC{l}_2,VOC{l}_2$

Answer 1

Answer: (D)

In $CuC{l}_2,C{u}^{2+}$ has $d^9$ configuration, exhibit $d-d$ transition and show colour. Similarly in $VOC{l}_2,V^{4+}$ has $d^1$ configuration, can exhibit $d-d$ transition and show colour.
$MnC{l}_2=$ Pink colour
$Z{n}^{2+}\Rightarrow 3d^{10}$ Colourless
$H{g}^{2+}\Rightarrow 5d^{10}$ Colourless
$V=4s^{2}3d^3$
$V^{4+}=4s^{0}3d^1(d-d)$ transition)
$C{u}^{+2}=d^9$ configuration = one unpaired $e^{-}$.
Since, in both $CuC{l}_2$ and $VOC{l}_2,C{u}^{2+}$ and $V^{4+}$ ion contain $1$ unpaired electron each, so their colour may be same.