Question

the formation of molecular complex BF3-NH3 results in a change in hybridisation of boron.....

Answer 1

in BF3 boron undergoes sp2 hybridization so one vacant p orbital is there
ammonia has lone pair of electrons

so nitrogen supplies its lone pair to vacant orbital of boran
so sp2 changes to sp3

Answer 2

Answer: From sp2 to sp3

Explanation:

The atomic number of boron is 5 & its electronic configuration in ground state is 1s2 2s2 2p1, & in excited state is 1s2 2s1 2p2 , this means its one s & 2 p orbital will take part in hybridization to form sp2 hybrid orbital.

Similarly N atom has atomic number of 7, with electronic configuration of 1s2 2s2 2p3 in its ground state & in it excited state it has sp3 hybridization.

Now according to the question Boron & Nitrogen in reactant stage has sp2 & sp3 hybridization respectively, but on the product side an adduct is formed, wherein Boron has changed it s hybridization to sp3 while Nitrogen remains in same sp3 hybridization