The correct sequence of ligands in the order of decreasing field strength is :
- NCS- > EDTA4- > CN- > CO
- CO > H2O > F- > S2-
- S2- > -OH > EDTA4- > CO
- -OH > F- > NH3 > CN-
Answer
(2) CO > H2O > F- > S2-
Solution
Spectrochemical series (increasing field strength):
I- < Br- < SCN- < Cl- < S2- < F- < OH- < C2O42- < H2O < NCS- < EDTA4- < NH3 < en < CN- < CO
(A): CO is the strongest, not the weakest ⇒ wrong
(B): CO > H2O > F- > S2- ⇒ correct
(C): S2- is among the weakest ⇒ wrong
(D): CN- is stronger than NH3, F-, OH- ⇒ wrong
Answer: (2)