Consider the number of unpaired electrons present in the given metal complexes respectively, [Cu(H₂O)6]2-, [Fe(CN)6]4-, [Cr(H₂O)6]2-, [NiCl₄]2-, [Co(NH₃)6]2-. Which one is the correct option?
1) [Cu(H₂O)6]2-
2) [Fe(CN)6]4-
3) [Cr(H₂O)6]2-
4) [NiCl₄]2-
5) [Co(NH₃)6]2-