Draw the orbital picture of Ethene
Each carbon has two half-filled orbitals in ground state (1s2, 2s2, 2px1 2py 1, 2pz 0). It has four half-filled orbitals in excited state since one electron is promoted from 2s to empty 2p orbital during chemical combination (1s2, 2s2, 2px1 2py 1, 2pz 0).
Now, one 2s and two 2p orbitals undergo sp2 hybridization to form three sp2 hybrid orbitals of equivalent energy and identical shape and size which take trigonal planar geometry with bond...