Question

Which of the following compounds will be coloured in solid state?

• A. Cu₂Cl₂
• B. ZnF₂
• C. CuF₂
• D. Ag₂SO₄

Answer 1

The correct option is C CuF₂

If we considered $Cu{F}_2$ the oxidation state of Cu is 2+ ,

$Cu:\left[Ar\right]3d^{10}4s^1$
$C{u}^{2+}:\left[Ar\right]3d^9$

There is one unpaired electron. This electron imparts colour to the compound. If all the electrons are paired up, the compound will not be colored.