Magnetic moment, $$\mu = \sqrt {n(n + 2)} $$ BM (where n = number of unpaired electrons)

Ethylene diaminetetraacetate (EDTA) ion is a hexadented ligand having four donor oxygen atoms and two donor nitrogen atoms

Spectrochemical series (as given in NCERT) :
$${L^ - } < B{r^ - } < SC{N^ - } < C{l^ - } < {S^{ - 2}} < {F^ - } < O{H^ - } < {C_2}{O_4}^{2 - } < {H_2}O < NC{S^ - } < EDT{A^{4 - }} < N{H_3} < en < C{N^ - } < CO$$

Electronic configuration of $$Cr:[Ar]3{d^5}4{s^1}$$

Electronic configuration of $$C{r^{2 + }}$$:[Ar]3d⁴

No. of unpaired electrons = 4

Spin only magnetic moment = $$\sqrt {n(n + 2)} $$

n = number of unpaired e^{$$ - $$}

Spin only magnetic moment = $$\sqrt {4(4 + 2)} $$

= $$\sqrt {24} $$ BM

= 4.9 BM