The electronic configuration of Cu(II) is 3d9 whereas that of Cu(I) is 3d10. Which of the following is correct?

Cu(II) is more stable than Cu(I) because it has a 2+ charge and is smaller than Cu(I). The electron density and effective nuclear charge is greater for Cu(II) and it forms stronger bonds(high hydration energy) and releases more energy and is more stable.

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