Ratio of hybrid orbitals to pure ‘p’ orbitals in Ethene molecule is

H2Csp2=Csp2H2Each ‘sp2’ carbon contains 3 'sp2' hybrid orbitals and 1 pure ‘p’ orbital ;H-atom utilizes its pure ‘s’ orbitals in bonding.Number of 'sp2' hybrid orbitals = 2×3 = 6Number of pure ‘p’ orbitals     = 2×1 = 2Number of pure ‘s’ orbitals     = 4×1 = 4Ratio of hybrid orbitals to pure ‘p’ orbitals = 6 : 2 = 3 : 1 ;