The correct order for the CFSE (numerical value ) for the following complexes is :
`{:("Complex",P,Q,R,S),("Formula",[CoF_(6)]^(3-),[Co(CN)_(6)]^(3-),[Co(NH_(3))_(6)]^(3+),[Co(H_(2)O)_(6)]^(3+)):}`

Options

A. `P gt Q gt R gt S`
B. `Q gt R gt S gt P`
C. `S gt R gt P gt Q`
D. ` R gt Q gt P gt S`

Answer

B

Explanation

CFSE depends on the relative magnitude of crystal field splitting, `Delta_(o)` and pairing energy, p and in turns `Delta_(o)` depends upon the field produced by ligand and charge on the metal ion. So, the other of increasing crystal field strength is `F^(-)lt H_(2)OltNH_(3) lt CN^(-)`. (Co is in `+3` oxidation state in all complexes) . Thus the (B) option is correct.