Ligand Binding

A strong field ligand is one that causes a large splitting of the d-orbitals in a coordination complex. This is determined by the spectrochemical series, which arranges ligands according to their field strength. Ligands higher in this series cause greater splitting. Here is a brief analysis of the given options:

In conclusion, NH₃ is the strong field ligand among the given options.

The crystal field splitting power of ligands is determined by their ability to split the d-orbitals of a central metal ion in a coordination complex. Strong field ligands cause a large split, whereas weak field ligands cause a smaller split. This property is related to the strength of the ligand in forming a coordinate bond with the metal ion.

The order of ligands in terms of increasing crystal field splitting power is determined by their position in the spectrochemical series. The typical order for the ligands given is: Cl^- < F^- < H₂O < CN^-.

Thus, the correct increasing order of crystal field splitting power of the given ligands is B < C < D < A.