Solution: The following reactions are used in batteries:I. 2H2(g) + O2(g) ⟶ 2H2O(l)                                                    Ecell = 1.23 VII. Pb(s) + PbO2(s) + 2H2SO4(aq) ⟶ 2PbSO4(s) + 2H2O(l)     Ecell = 2.04 VIII. 2Na(l) + FeCl2(s) ⟶ 2NaCl(s) + Fe(s)                                Ecell = 2.35 VReaction I is used in fuel cells, II in the automobile lead-acid battery, and III in an experimental high-temperature battery for powering electric vehicles. The aim is to obtain as much work as possible from a cell, while keeping its weight to a minimum. (b) Calculate the ratio, in kJ/g, of wmax to mass of reactants for each of the cells. Which has the highest ratio, which the lowest, and why? (Note: For simplicity, ignore the masses of cell components that do not appear in the cell as reactants, including electrode materials, electrolytes, separators, cell casing, wiring, etc.)