If C(diamond) \(\rightarrow\) C(graphite) + \(X\text{kJ mol}^{-1}\)C(diamond) +\( O_2(g)\) \(\rightarrow\) \(CO_2(g) + Y\text{kJ mol}^{-1} \)C(graphite) + \(O_2(g)\) \(\rightarrow\) \(CO_2(g) + Z\text{kJ mol}^{-1}\) at constant temperature, then