[" Q.11.10.Why does R "_(3)P=" O exist but "R_(3)N=0" does not "(R=" alkyl group) "?],[" Ans.N dueto the absence of corbititals cannot form "p pi-d pi" multiple bonds."],[" covalency beyond four but in "R_(3)N=O,N" has a covalency of "5." Therefor "]