Chemistry - Coordination Chemistry Question with Solution | TestHub

In $[Co(N{H}_3{)}_6{]}^{3+}$, Co is in the $+3$ oxidation state:

$C{o}^{3+}=3d^6$

$N{H}_3$ is a strong field ligand, so pairing occurs, and the complex forms an inner orbital octahedral complex with $d^{2}s{p}^3$ hybridization of metal orbitals. The ligand $N{H}_3$ donates its lone pair from an $s{p}^3$ hybrid orbital into the vacant orbital of $C{o}^{3+}$.

Correct answer: A $\to s{p}^3$