Question

Among the following the compounds, one that is both paramagnetic and coloured, is:

• A. $K_{2}C{r}_2{O}_7$
• B. $K_2\left[TiC{l}_6\right]$
• C. $VOS{O}_4$
• D. $K_3\left[Cu\right(C{N}_4\left)\right]$
• E. none

Answer 1

The correct option is C $VOS{O}_4$

Considering the electronic configuration of the central atom of the given complexes-

(A) $K_2{Cr}_2{O}_7\to {Cr}^{6+}\left[3s^{2}3p^6\right]$

(B) $K_2\left[TiC{l}_6\right]\to {Ti}^{4+}\left[3s^{2}3p^6\right]$

(C) $VOS{O}_4\to V^{4+}\left[3s^{2}3p^{6}3d^1\right]$

(D) $K_3{[Cu}_2\left({CN)}_4\right]\to {Cu}^{+}\left[3s^{2}3p^{6}3d^{10}\right]$

None of the metals have unpaired electrons ie. all of them are diamagnetic except for $V^{4+}$

It has 1 unpaired electron which makes it paramagnetic.

Also, the transition of this unpaired electron makes it a coloured compound.