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Q.
The ion of least magnetic moment among the following is
J & K CETJ & K CET 2009The d-and f-Block Elements
Solution:
Magnetic moment depends upon the number of unpaired electrons.
Lower the number of unpaired electrons, least is the magnetic moment.
$T i^{3+}=[A r] 3 d^{1} 4 s^{0}$ (One unpaired electron)
$N i^{2+}=[A r] 3 d^{8}, 4 s^{0}$ (Two unpaired electrons)
$C o^{2+}=[A r] 3 d^{7}, 4 s^{0}$ (Three unpaired electrons)
$M n^{2+}=[A r], 3 d^{5}, 4 s^{0}$ (Five unpaired electrons)
Thus, $T i^{3+}$, due to the presence of least number of unpaired electrons, has the least magnetic moment, among the given ions.