D-And F-Block Elements Ques 405
Question: Which of the following species is expected to show the highest magnetic moment- (At. Nos.: Cr=24, Mn = 25, Co = 27, Ni = 28, Cu = 29)
[Kerala PMT 2004]
Options:
A) $ C{{r}^{2+}} $
B) $ M{{n}^{2+}} $
C) $ C{{u}^{2+}} $
D) $ C{{o}^{2+}} $
E) $ N{{i}^{2+}} $
Show Answer
Answer:
Correct Answer: B
Solution:
Highest magnetic moment depends upon number of unpaired electron since $ C{{r}^{2+}}=3d^{4}4s^{0} $ ,
$ M{{n}^{2+}}=3d^{5}4s^{0} $
$ C{{u}^{2+}}=3d^{9}4s^{0} $ ,
$ C{{o}^{2+}}=3d^{7}4s^{0} $ ,
$ N{{i}^{2+}}=3d^{6}4s^{0} $
So $ M{{n}^{2+}} $ contain maximum number of unpaired electron i.e. 5.
