Electronic configuration of Cu(II) is $$3d^9$$ whereas that of Cu(I) is $$3d^{10}$$. Which of the following is correct?

Cu(II) has configuration $$3d^9$$ and Cu(I) has $$3d^{10}$$.

Although Cu(I) has a fully filled $$3d^{10}$$ configuration (which is stable), Cu(II) is actually more stable in aqueous solution. This is because the higher hydration enthalpy of Cu²⁺ (due to its smaller size and higher charge) more than compensates for the second ionization energy required.

The high hydration energy of Cu²⁺ stabilizes it in aqueous solutions. Cu(I) compounds tend to disproportionate in water: $$2Cu^+ \rightarrow Cu + Cu^{2+}$$.

The correct answer is Option 2: Cu(II) is more stable.