To calculate the standard enthalpy of formation of methane gas CH4 , we need to consider the bonds broken and bonds formed during the reaction. The formation of methane involves the combination of one carbon atom and four hydrogen atoms.The given bond energies are:C-C = 347 kJ/molC-H = 413 kJ/molIn the formation of methane, there are no C-C bonds involved, so we don't need to consider the C-C bond energy. However, there are four C-H bonds formed in methane.Using the formula Hf = bonds broken - bonds formed :Hf = 0 - 4 * 413 kJ/mol Hf = -1652 kJ/molThe standard enthalpy of formation of methane gas CH4 is -1652 kJ/mol.