The pair in which both species have same magnetic moment (spin...

The pair in which both species have same magnetic moment (spin onlyvalue) is:

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A $\left[\mathrm{Cr}$ \left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}, $\left[\mathrm{CoCI}_{4}\right]^{2-}$
B $\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}_{6}\right)^{2+},\left[\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+}\right.$
C $\left[\mathrm{Mn}$ \left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right)^{2+}, $\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}$
D $\left[\mathrm{CoCl}_{4}\right)^{2-},$ \left[\mathrm{Fe} $\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}$

B. $\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}_{6}\right)^{2+},\left[\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+}\right.$

\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+} \mathrm{Cr}

is in

\mathrm{Cr}^{2+}

form

\left[\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{2+} \mathrm{Fe}^{2+}

form. Both will have 4 unpaired electrons.