Which of the following compounds is expected to be coloured?
Which of the following compounds is expected to be coloured?
$\mathrm{ZnSO}_4$
$\mathrm{MgCl}_2$
$\mathrm{CuCl}_2$
$\mathrm{AgCl}$
Solution
Copper chloride $\left(\mathrm{CuCl}_2\right)$ as a yellow-brown powder (in anhydrous form) or a green crystalline solid (in dihydrate form) due to copper exist as divalent $\mathrm{Cu}^{2+}$ ions with $3 d^9$ electronic configuration. Due to presence of 1 unpaired electron in $3 d$-orbital, it is coloured.
Remaining $\mathrm{ZnSO}_4, \mathrm{MgCl}_2$ and $\mathrm{AgCl}$ are not coloured compounds respectively.
Hence, only $\mathrm{CuCl}_2$ is expected to be coloured.