The hybridized orbital in SeBr4 molecule is?

Question

sp2

sp3

sp2d

sp3d2

Answer 1

The question is phrased somewhat oddly.  SeBr4 has 34 electrons and four bonds, and four species with octets of electrons.  That means that there is a lone pair on the central Se atom.  This means there are five electron pairs on Se, which produces a trigonal pyramidal electron pair geometry.  This in turn, indicates that Se will have sp3d hybridization.  

So unless your answers have a typo, the correct answer isn't on your list.

The hybrid orbitals sp2, sp3 and sp3d2 are real hybridizations.  But sp2d is not.  I think that is where the typo is, and that it should be sp3d.