Q25 / 150 · MHT CET 2026 (18 April Shift 1) · Chemistry
Identify a ligand with highest field strength among the following.
- A$\text{H}_2\text{O}$
- Correct answerB$\text{NH}_3$
- C$\text{S}^{2-}$
- D$\text{NCS}^-$
Solution
According to the spectrochemical series, the arrangement of ligands in the increasing order of their crystal field splitting energy (CFSE) values is:
$I^- < Br^- < SCN^- < Cl^- < S^{2-} < F^- < OH^- < C_2O_4^{2-} < H_2O < NCS^- < edta^{4-} < NH_3 < en < CN^- < CO$
From the given options, the order of field strength is $S^{2-} < H_2O < NCS^- < NH_3$.
Thus, $\text{NH}_3$ has the highest field strength.
Answer: $\text{NH}_3$
$I^- < Br^- < SCN^- < Cl^- < S^{2-} < F^- < OH^- < C_2O_4^{2-} < H_2O < NCS^- < edta^{4-} < NH_3 < en < CN^- < CO$
From the given options, the order of field strength is $S^{2-} < H_2O < NCS^- < NH_3$.
Thus, $\text{NH}_3$ has the highest field strength.
Answer: $\text{NH}_3$
Hence, the correct answer is option: 'B'.