The species in which the central atom uses sp2−hybrid orbitals in its bonding is

In  CH3+,  carbon  atom  is in  sp2−hybridized  state.H=12V+X−Ca PH3=12 5+3=4⇒ sp3b NH3=12 5+3=4⇒ sp3c CH3+=12 4+3−1=3⇒ sp2a SbH3=12 5+3=4⇒ sp3Where, V=number of valence shell electrons of central atom.             X = number of monovalent atoms.             C = Charge on the species(including sign)