question_answer

A complex of a certain metal ion has a magnetic moment of\[4.90BM\]. Another complex of the same metal ion in the same oxidation state has \[2.8\text{ }BM\]magnetic moment. The central metal ion could be which of the following?

A) \[C{{r}^{3+}}\]        

B)                    \[M{{n}^{3+}}\]           

C) \[F{{e}^{2+}}\]                 

D)        \[C{{o}^{2+}}\]

Correct Answer: B

Solution :

[b] \[\mu =4.9\] BM corresponds to \[n=4\]and for \[\mu =2.80\] BM corresponds to\[n=2\]. For \[{{d}^{4}}\] configuration, in a weak fields ligands it will have 4 unpaired electrons. In strong field ligand, \[{{d}^{4}}\]configuration will have one paired electrons and two unpaired electrons. Note:- \[{{d}^{1}}\] to \[{{d}^{3}}\] configuration, no pairing will occur whether the ligand field is weak or strong. But for \[{{d}^{4}}\]configuration only one pairing will occur in strong field ligands Therefore, \[M{{n}^{3+}}\] have \[3{{d}^{4}}\] configuraton. In weak field ligands: In strong field ligands: