50

26Fe 1s2 2s2 3s2 3p6 3d6 4s2
1s2 2eff=26-0.35=25.65
2s22p6 26-4.15=21.85
3s23p6 26-11.25=14.75
3d6 26-18x1.00-5x0.35=6.35
4s2 26-10x1.00-14x0.85-0.35=26-22.25=3.75
Sum of Zeff=25.65+21.85+4/9x14.75+3/9x6.35+1/16x3.85
=56.19
amegnetic curectim=3.552x10-5x56.19=2.00x10-3
haitree value=2.02x10-3
thomas ferris value=2.46x10-3
0.259