Question
The magnitude of $$CFSE$$ ( crystal field splitting energy, $${\Delta _o}$$ ) can be related to the configuration of $$d$$ - orbitals in a coordination entity as
A.
If $${\Delta _o} < P,$$ the configuration is $$t_{2g}^3\,e_g^1 = $$ weak field ligand and high spin complex
B.
if $${\Delta _o} > P,$$ the configuration is $$t_{2g}^3\,e_g^1 = $$ strong field ligand and low spin complex
C.
if $${\Delta _o} > P,$$ the configuration is $$t_{2g}^4\,e_g^0 = $$ strong field ligand and high spin complex
D.
if $${\Delta _o} = P,$$ the configuration is $$t_{2g}^4\,e_g^0 = $$ strong field ligand and high spin complex.
Answer :
If $${\Delta _o} < P,$$ the configuration is $$t_{2g}^3\,e_g^1 = $$ weak field ligand and high spin complex
Solution :
If $$CFSE\left( {{\Delta _o}} \right) < P$$ ( Energy required for pairing ), the electrons do not pair up and fourth electron goes to $${e_g}$$ of higher energy. Hence, high spin complex is formed. Pairing of electrons does not take place in case of weak field ligands