The magnetic moment of a complex ion is 2.83 B.M. The complex ion is :

μ→=2.83BM⇒ Number of unpaired e−must be =2 (a) VH2O63+     Number of unpaired e−=2 (b) CrH2O63+     Number of unpaired e−=3 (c) Cu(CN)42−     Number of unpaired e−=1 (d) MnCl42−     Number of unpaired e−=5