The correct increasing order of stability of the complexes based on Δ_o value is: I. [ Mn ( CN )_6]^3- II. [ Co ( CN )_6]^4- III. [ Fe ( CN )_6]^4-…

The correct increasing order of stability of the complexes based on $\displaystyle \Delta_{\mathrm{o}}$ value is : I. $\displaystyle \left[\mathrm{Mn}(\mathrm{CN})_6\right]^{3-}$ II. $\displaystyle \left[\mathrm{Co}(\mathrm{CN})_6\right]^{4-}$ III. $\displaystyle \left[\mathrm{Fe}(\mathrm{CN})_6\right]^{4-}$ IV. $\displaystyle \left[\mathrm{Fe}(\mathrm{CN})_6\right]^{3-}$