The standard enthalpy of formation (∆_fH^o)  at 298 K for methane, CH₄(g), is –74.8 kJ mol^–1. The additional information required to determine the average energy for C – H bond formation would be

• the dissociation energy of H₂ and enthalpy of sublimation of carbon

• latent heat of vapourization of methane

• the first four ionization energies of carbon and electron gain enthalpy of hydrogen

• the dissociation energy of hydrogen molecule, H₂