(i) Mn (z = 25), Mn4+ (z = 21)
The electronic configuration of Mn4+ to Given by
1s2 2s2 2p6 3s2 3p6 3d3
As the outermost shell 3d has 3 electrons, thus the number of unpaired electrons is 3.
(ii) Fe (z = 26), Fe3+ (z = 23)
The electronic configuration of Fe3+ is given lay
1s2 2s2 2p6 3s2 3p6 3d5
The number of unpaired electron is 5.
(iii) Cr (z = 24), Cr2+ (z = 22)
The electronic configuration of Cr2+ is
1s2 2s2 2p6 3s2 3p6 3d4
The number of unpaired electron is 4.
(iv) Zn (z = 30), Zn2+ (z = 28)
The electronic configuration of Zn2+ is
1s2 2s2 2p6 3s2 3p6 3d10
The number of unpaired electron is 0.
