Question

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

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

Answer 1

The correct option is B

$VOC{l}_2,CuC{l}_2$

In transition element series, colour is observed due to d-d transition of d orbital electrons so compounds with same number of unpaired electron will shown same colour. Both $V^{4+}\left({\left[Ar\right]}^{18}{d}^{1}4s^0\right)$ and ${Cu}^{2+}\left({\left[Ar\right]}^{18}{d}^{1}4s^0\right)$ and thus exhibit same colour.