Total number of unpaired electrons \(=5\)
\(\mu\) (Magnetic moment) \(=\sqrt{ n ( n +2)} BM\)
where \(n =\) number of unpaired \(e ^{-}\)
\(\therefore \mu=\sqrt{5(5+2)}=\sqrt{35} BM =5.92 BM\)
$(I)$ $\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right] \mathrm{Br}_{2}$
$(II)$ $ \mathrm{Na}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]$
$(III)$ $\mathrm{Na}_{3}\left[\mathrm{Fe}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right]\left(\Delta_{0}>\mathrm{P}\right)$
$(IV)$ $\left(\mathrm{Et}_{4} \mathrm{N}\right)_{2}\left[\mathrm{CoCl}_{4}\right]$