Arrange the following ligands in order of increasing field strength on the basis of spectrochemical series.
A. NH3
B. CO
C. C2O42−
D. EDTA4−
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → C, D, A, B
The spectrochemical series arranges ligands in order of increasing field strength, that is, their ability to split the d orbitals of the metal. Taking the given ligands from this series:
C: \( \ce{C2O4^{2-}} \) (oxalate): weakest of the four
D: EDTA4−
A: \( \ce{NH3} \)
B: CO: strongest ligand in the series
Shortcut: CO is the strongest ligand, so it must come last. Only Option (4) ends with B.
NCERT (2026-27 edition):
Crystal Field Theory – …
