The CFSE for octahedral [CoCl6]4– is 18,000 cm–1. The CFSE for tetrahedral [CoCl4]2– will be
Crystal field splitting energy for tetrahedral is 
times that for octahedral
∆t= 
∆o
∆t= 
×18,000 cm–1=8,000 cm–1
Thus, Option C is the correct answer.
1
The CFSE for octahedral [CoCl6]4– is 18,000 cm–1. The CFSE for tetrahedral [CoCl4]2– will be
Crystal field splitting energy for tetrahedral is times that for octahedral
∆t= ∆o
∆t= ×18,000 cm–1=8,000 cm–1
Thus, Option C is the correct answer.