The hybridisation of metals involved in the following complexes, respectively are…
- $s p^3 d^2, s p^3 d^2$
- $s p^3 d^2, d^2 s p^3$
- $d^2 s p^3, d^2 s p^3$
- $d^2 s p^3, s p^3 d^2$
Solution

As $\mathrm{CN}^{-}$is a strong field ligand, it causes pairing of two $3 d$ electrons, thereby making two $d$-orbitals vacant, namely $d_{x^2-y^2}$ and $d_{z^2}$. These two $d$-orbitals and one $4 s$ and three $4 p$-orbitals hybridise and give $d^2 s p^3$-hybridisation. In $\left[\mathrm{Co}(\mathrm{F})_6\right]^{3-}, \mathrm{Co}$ is in +3 oxidation state.

As $\mathrm{F}^{-}$is a weak field ligand, so it cannot cause the pairing of unpaired $3 d$-electrons. Thus, one $4 s$, three $4 p$-orbitals and two $4 d$-orbitals hybridise and give $s p^3 d^2$-hybridisation.
Asked in: AP EAMCET 2022 (07 Jul Shift 2)