The magnetic moment is associated with its spin angular momentum and orbital angular momentum. Spin only magnetic moment value of $$C{r^{3 + }}$$  ion is

Solution :
$$\eqalign{ & Cr\left( {24} \right):3{d^5}4{s^1} \cr & C{r^{3 + }}:3{d^3} \cr & \mu = \sqrt {n\left( {n + 2} \right)} \cr & \,\,\,\,\, = \sqrt {3\left( {3 + 2} \right)} \cr & \,\,\,\,\, = \sqrt {15} \cr & \,\,\,\,\, = 3.87\,B.M. \cr} $$