How do you find unpaired electrons in a metal ion in CuSO4·5H20?

Answer 1

You write the electron structure like this.
1s2 2s2 2p6 3s2 3p6 3d10 4s1 is the neutral Cu atom.
Remove the two outside electrons to make the Cu^+2 ion. That leaves us with
3d9 as the outside and since that is an odd number, one electron must be unpaired. And you will note that many Cu(II) compounds are colored.