In which of the following coordination entities the magnitude of o (CFSE in octahedral field) will be maximum? (At. no. Co = 27) [CBSE AIPMT2007]

The magnitude of crystal field splitting energy depends is decided by the nature of ligand. Strong field ligand exhibits highest crystal field splitting energy and the increasing field strength of the ligands are as CN–>NH3>C2O4 –2>H2O. Since, CN is the strongest ligand among others, Hence, option (c) will have the highest crystal field splitting energy. Therefore the correct option is (c).