$\left[\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{3} \mathrm{Cl}_{3}\right] \rightarrow$ Outer-orbital complex



$\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right] \mathrm{Cl}_{3} \rightarrow$ Inner-orbital complex

Since $\mathrm{CN}^{-}$is a strong field ligand than $\mathrm{NH}_{3}$. Hence $\mathrm{K}_{3}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]$ is the inner-orbital complex that absorbs light at shortest wavelength.

$\mathrm{Fe}(\text{III}) \rightarrow$ valence shell configuration $3 \mathrm{~d}^{5}$

Since $\mathrm{CN}^{-}$will do pairing, so unpaired electron $=1$