Q.
The standard enthalpy of formation (ΔHf∘) 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:
Carbon is found in solid state. The state ol substance affects the enthalpy change. C(S)→C(g) Sublimation
and H2(g)→2H(g) dissociation
are required for C—H bond