Key Idea For sp2 hybridisation, there must be 3σ-bonds or 2σ-bonds along with a lone pair of electrons. (i) NO2−⇒2σ+1lp=3, ie, sp2 hybridisation (ii) NH3⇒3σ+1lp=4, ie, sp3 hybridisation (iii) BF3⇒3σ+0lp=3, ie, sp2 hybridisation (iv) NH2−⇒2σ+2lp=4, ie, sp3 hybridisation (v) H2O⇒2σ+2lp=4, ie, sp3 hybridisation Thus, among the given pairs, only BF3 and NO2− have sp2 hybridisation.