Explain the following giving an appropriate reason in each case.
Structure of xenon fluorides cannot be explained by valence bond approach.

Explanation

The number of electrons present in the valence shell of Xe in `XeF_(6) = 8 + 6 = 14` electrons = 7 electron pairs = 6 bond-pairs + 1 lone-pair `=sp^(3)d^(3)` - hybridisation. Now, because of `sp^(3)d^(3)` -hybridisation the six bond-pairs and one lone-pair may be oriented in three different ways. However, the actual shape of `XeF_(6)` in vapour state is symmetrical octahedral.. Thus, valence bond theory cannot explain the structure, i.e., the shape of `XeF_(6)` molecule.