Chemistry - CHEMICAL BONDING Question with Solution | TestHub

$\mathrm{B}-\mathrm{F}$bond length in${\mathrm{BF}}_3$is found to be less than theoretical value because the electronegativity values of$\mathrm{B}\left(2.04\right)$and$\mathrm{F}\left(4.0\right)$suggest the bond length to be ionic and hence, the attraction between oppositely charged ions must decrease the bond length.

${\mathrm{BF}}_3$and${\left[{\mathrm{BF}}_4\right]}^{-}$have equal$\mathrm{B}-\mathrm{F}$bond length.

The decrease in the$\mathrm{B}-\mathrm{F}$bond length in${\mathrm{BF}}_3$is due to delocalised$\text{p}\pi -\text{p}\pi$bonding between vacant$2\mathrm{p}$orbital of$\mathrm{B}$and filled$2\mathrm{p}$orbital of$\mathrm{F}$

The correct$\mathrm{B}-\mathrm{X}$bond length order is$\mathrm{B}-\mathrm{F}>\mathrm{B}-\mathrm{Cl}>\mathrm{B}-\mathrm{Br}>\mathrm{B}-\mathrm{I}$