Final answer:
The structural isomers C2H5OH (ethanol) and CH3OCH3 (dimethylether) would have the same gaseous densities at the same temperature and pressure, due to having identical molecular weights. This is in spite of their differing boiling points, vapor pressures, and heats of vaporization caused by varying intermolecular forces, particularly the hydrogen bonding present in ethanol.
Step-by-step explanation:
The structural isomers in question are C2H5OH (ethanol) and CH3OCH3 (dimethylether), which are molecules with the same molecular formula but different structures and chemical properties due to the arrangement of their atoms. This type of isomerism affects various physical properties, including boiling points, melting points, vapor pressures, and other characteristics due to differences in intermolecular forces. Considering ideal behavior and molecular properties, these two isomers would be expected to have the same gaseous densities at the same temperature and pressure as they have the same molecular weight.
Despite their identical molecular formulas, ethanol and dimethylether have different boiling points, melting points, vapor pressures, and heats of vaporization due to the presence of hydrogen bonding in ethanol which increases its intermolecular forces relative to dimethylether. Since the question assumes ideal behavior, the best choice for the value that would be the same for both isomers is (A) Gaseous densities at the same temperature and pressure.