Determining the exact excited electronic state and associated wavelength of light for a molecular system like CH2O formaldehyde is a complex task that typically requires advanced computational methods and experimental data. However, I can provide some general information on the topic.In general, the excited electronic states of a molecule are determined by the promotion of an electron from a lower energy molecular orbital to a higher energy molecular orbital. For formaldehyde, the ground state electronic configuration is described by the molecular orbitals formed from the atomic orbitals of carbon, hydrogen, and oxygen atoms.The lowest excited electronic state for formaldehyde is the result of promoting an electron from the highest occupied molecular orbital HOMO to the lowest unoccupied molecular orbital LUMO . This transition is typically denoted as * from a bonding orbital to an antibonding * orbital .The associated wavelength of light for this transition can be estimated using the energy difference between the HOMO and LUMO orbitals. This energy difference corresponds to the energy of a photon that can be absorbed by the molecule to promote the electron to the excited state. The relationship between energy E and wavelength of a photon is given by the equation:E = h * c / where h is the Planck's constant 6.626 x 10^-34 Js and c is the speed of light 2.998 x 10^8 m/s .To determine the exact energy difference between the HOMO and LUMO orbitals and the associated wavelength of light for formaldehyde, one would need to perform quantum chemical calculations or consult experimental data. However, it is worth noting that * transitions typically fall in the ultraviolet UV region of the electromagnetic spectrum, with wavelengths ranging from around 100 to 400 nm.