To determine the combined energy absorbed for the reactant side of the equation, we need to calculate the energies needed to break the bonds in CH4 and Cl2.
The bond energy of CH4 is 435 kJ/mol (4 C-H bonds).
The bond energy of Cl2 is 243 kJ/mol (1 Cl-Cl bond).
Adding these two values together, we get:
435 kJ/mol + 243 kJ/mol = 678 kJ/mol
Therefore, the combined energy absorbed for the reactant side of the equation is 678 kJ/mol. None of the provided answer options match this value.