The type of hybridisation of boron in diborane is (AIPMT 1999)

Each ‘B’ atom in diborane (B₂H₆) is sp3hybridised. Of the 4-hybrid orbitals, three have one electron each, while the 4th is empty. Two orbitals of each form s bonds with two ‘H’-atoms, while one of the remaining hybrid orbital (either filled or empty), 1s orbital of ‘H’ atom and one of the hybrid orbitals of other ‘B’ atom overlap to form three centered two electron bond. So there exists two such type of three centered bonds.