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Q.
The spin only magnetic moment value (in $ $B.M.$ $ unit) of $ Cr(CO)_{6} $ is
IIT JEEIIT JEE 2009Coordination Compounds
Solution:
In $Cr(CO)_{6}$, $Cr$ is present as $Cr^{0}$
$Cr$ or $Cr^{0}=[Ar] 3d^{5} \, 4S^{1}$
$CO$ being strong field ligand pair up the unpaired electrons of $Cr$
In this condition,
number of unpaired electrons, $n=0$
Magnetic moment, $\mu= \sqrt{n\left(n+2\right)}$
$=\sqrt{0\left(0+2\right)}$
$=0\, BM$
