Chemistry - Complete d-block Question with Solution | TestHub

Given magnetic moment $=4.9$ B.M.
We know M.M $=\sqrt{\mathrm{n}(\mathrm{n}+2)}$ B.M.
Where, $\mathrm{n}\to$ No. of unpaired ${\mathrm{e}}^{-}$
$4.9=\sqrt{\mathrm{n}(\mathrm{n}+2)}$
We get $\mathrm{n}=4$
(A) ${}_{24}{\mathrm{Cr}}^{2+}\Rightarrow [\mathrm{Ar}]3{\mathrm{d}}^4$ (4 unpaired e)
(B) ${}_{26}{\mathrm{Fe}}^{2+}\Rightarrow [\mathrm{Ar}]3{\mathrm{d}}^6$ (4 unpaired e)
(C) ${}_{26}{\mathrm{Fe}}^{3+}\Rightarrow [\mathrm{Ar}]3{\mathrm{d}}^5$ (5 unpaired e)
(D) ${}_{27}{\mathrm{Co}}^{2+}\Rightarrow [\mathrm{Ar}]3{\mathrm{d}}^7$ (3 unpaired ${\mathrm{e}}^{-}$)
(E) ${}_{25}{\mathrm{Mn}}^{3+}\Rightarrow [\mathrm{Ar}]3{\mathrm{d}}^4(4$ unpaired ${\mathrm{e}}^{-})$