D-And F-Block Elements Ques 323
Question: Which of the following ions has the least magnetic moment
[MP PMT 1993]
Options:
A) $ C{{u}^{+2}} $
B) $ N{{i}^{+2}} $
C) $ C{{o}^{+3}} $
D) $ F{{e}^{+2}} $
Show Answer
Answer:
Correct Answer: A
Solution:
| S.No | Ion | Electronic configuration | No. of unpaired electrons |
|---|---|---|---|
| (i) | $ C{{u}^{+2}} $ | $ d^{9} $ | 1 |
| (ii) | $ N{{i}^{+2}} $ | $ d^{8} $ | 2 |
| (iii) | $ C{{o}^{+2}} $ | $ d^{7} $ | 3 |
| (iv) | $ F{{e}^{+2}} $ | $ d^{6} $ | 4 |
$ \mu =\sqrt{n(n+2)} $ (magnetic moment) $ \mu \propto \sqrt{n} $
$ C{{u}^{+2}} $ there is only 1 unpaired electron so its magnetic moment is least.
