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. (a) Calculate a formula for the unknown gas, and write a balanced equation for the combustion reaction.