Write the structure and hybridisation of the central atom in `[CoCl_2 (NH_3)_4]`

Explanation

O.S. of Co in the complex = +2
E.C. of Co (Z = 27): `[Ar]^(18)3d^7 4s^2`
E.C. of `Co^(2+)`: `[Ar]^(18)3d^7`
With 7-electrons in 3d-subshell, pairing is not possible in case of an octahedral complex. As such hybridisation is `sp^3d^2` and the complex is octahedral.