In the molecule, c2h4, what are the atomic
orbitals that participate in forming the sigma
bond between the c and h atoms

Ethene (C2H4) is an alkene which means this compound has a double bond between the carbons. The hybridization hence is sp2. In this hybridization, the 2s orbital mixes with only two of the three available 2p orbitals, forming a total of 3 sp2 orbitals with one p-orbital remaining.

Determine the  wavelength of light emitted when an electron  in an li2+ ion  makes a transition from an orbital with n  =  6 to an orbital with n  = 5.