Arrange the following ligand in the order of increasing field strength. H 2 O CO NH 3 I - F - I II III IV V

Spectrochemical series: A list of ligands ordered in ligand strength and a list of metal ions based on oxidation number, group, and identity.

Using the concept of spectrochemical series, the ligands arranged in increasing order of crystal field strength are,

${\mathrm{I}}^{-}<{\mathrm{F}}^{-}<{\mathrm{H}}_2\mathrm{O}<{\mathrm{NH}}_3<\mathrm{CO}$

If in a complex, at least one ligand is strong field ligand, in this case, all ligands are considered as strong field ligand.