Question

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

• A. $VOC{l}_2$; $FeC{l}_2$
• B. $CuC{l}_2$; $VOC{l}_2$
• C. $MnC{l}_2;FeC{l}_2$
• D. $FeC{l}_2;CuC{l}_2$

Answer 1

Answer: (B)

$CuC{l}_2$; $VOC{l}_2$

$V^{4+}$ and $C{u}^{2+}$ both have one unpaired electron available. Hence, they give the same colour (blue colour) in solution.

$V^{4+}$ has outer electronic configuration of $3d^1$ and $C{u}^{2+}$ has outer electronic configuration of $3d^9$.

Thus, both have 1 unpaired electron.
Option (B) is correct.