A sample of the sugar d-ribose (C5H10O5) of mass 0.727 g was placed in a calorimeter and then ignited in the presence of excess oxygen. The temperature rose by 0.910 K. In a separate experiment in the same calorimeter, the combustion of 0.825 g of benzoic acid, for which the internal energy of combustion is 3251 kJ mol1, gave a temperature rise of 1.940 K. Calculate the internal energy of combustion of d-ribose and its enthalpy of formation.