When a gaseous compound X containing only C, H, and O is burned in O2, 1 volume of the unknown gas reacts with 3 volumes of O2 to give 2 volumes of CO2 and 3 volumes of gaseous H2O. Assume all volumes are measured at the same temperature and pressure. (d) Combustion of 5.000 g of X releases 144.2 kJ heat. Look up ΔH°f values for CO21g2 and H2O1g2 in Appendix B, and calculate ΔH°f for compound X.