Number of unpaired electron are given by
Magnetic moment = √n(n+2)
Where n is the No. of unpaired electrons
Or 1.73 = √n(n+2)
1.73×1.73=n2+2n
∴ n = 1
Vanadium atom must have one unpaired electron and thus its configuration is
23V4+:1s2,2s22p6,3s23p63d1