Explanation

(b)
$Zn(30) = \lbrack Ar\rbrack 3d^{10},4s^{2}$
$Zn^{2 +} = \lbrack Ar\rbrack 3d^{10}\ \ \ \$(no unpaired electron)
$Fe(26) = \lbrack Ar\rbrack 3d^{6},4s^{2}$
$Fe^{2 +} = \lbrack Ar\rbrack 3d^{6}$
$3d^{6}$ [image:2_image33.emf]
(four unpaired electrons)
$Ni(28) = \lbrack Ar\rbrack 3d^{8},4s^{2}$
$Ni^{3 +}\lbrack Ar\rbrack 3d^{7}$
$3d^{7}$ [image:2_image34.emf]
(three unpaired electrons)
$(Cu(29) = \lbrack Ar\rbrack 3d^{10},4s^{1}$
$Cu^{+} = \lbrack Ar\rbrack 3d^{10}\$ (no unpaired electron)