The octahedral complex of a metal ion M3+ with four Monodentate Ligands, L1, L2, L3 and L4 absorb wavelengths in the region of red, green, yellow and blue respectively. The increasing order of ligand strength of the four ligands is
-
L4< L3<L2<L1
-
L1<L3<L2<L4
-
L3<L2<L4<L1
-
L1<L2<L4<L3
B.
L1<L3<L2<L4

λ | L1 | L2 | L3 | L4 |
Absorbed light | Red | Green | Yellow | Blue |
Therefore, increasing order of energy of wavelengths abosrbed reflects greater extent of crystal - field splitting, hence higher field strength of the ligand.
Energy: Blue(L4)> Green (L2)> Yellow (L3) > Red (L1)