The bond dissociation energy of B - F in BF_(3) is 646 KJ mol^(-1) whereas that of C-F in CF_(4) is 515 kJ mol^(-1) . The correct reason for higher B - F bond dissociation energy as comparad to that of C - F is

The bond dissociation energy of B - F in BF_(3) is 646 KJ mol^(-1) whe

1.	The bond dissociation energy of B - F in BF_(3) is 646 KJ mol^(-1) whereas that of C-F in CF_(4) is 515 kJ mol^(-1) . The correct reason for higher B - F bond dissociation energy as comparad to that of C - F is
Answer» smallarsize of B-atom as compared to that of C-atom STRONGER `sigma`-bond between B and F in `BF_(3)`as compared to that between C and F in `CF_(4)` significant `ppi-ppi` interaction between B and F in`BF_(3)` whereas there is no possibility of such interaction between C and F in `CF_(4)` lower degree of `ppi-ppi` interaction between B and F in `BF_(3)` than between C and F in `CF_(4) ` Solution :The empty `2p_(z)` orbitals of B which is not involved in the hybridisation can accept an electron pair from a FULL `2p_(z)` orbitals of any F-atom , formaing ` pi`-bond . Thus , B-F bondlength becomes shorter. HENCE, bond is stronger and dissociation energy is higher .