Answer :
Final answer:
The increasing order of ligand strength is L3 < L2 < L1. The correct option is 4. L3 < L2 < L1.
Explanation:
The color of coordination complexes is influenced by the specific ligands coordinated to the metal center. Strong-field ligands cause a large split in the energies of d orbitals of the central metal atom, resulting in absorption of higher-energy violet or blue light. Weak-field ligands, on the other hand, cause a smaller split and absorb lower-energy yellow, orange, or red light.
In this specific scenario, L1 absorbs green light, L2 absorbs blue light, and L3 absorbs red light. Since L3 absorbs the highest-energy light, it has the strongest ligand strength, followed by L2, and then L1.
