Final answer:
Entropy is influenced by molecular complexity, physical state, and temperature. Typically, larger, more complex molecules in the gaseous state have higher entropies. The substance CH₃OH(g) mentioned by the student should have high entropy due to its gaseous state and molecular complexity, though for an exact comparison, specific options must be provided.
Step-by-step explanation:
The student asked which substance is expected to have the greatest standard molar entropy. Entropy is a measure of the disorder or randomness in a system, and it tends to increase with the number of available microstates that a substance's particles can occupy. We determine it by looking at the molecular complexity, physical state, and temperature. In this context, substances with higher molar masses and more complex molecular structures in the gaseous state at higher temperatures usually have higher entropies.
Given the options: a larger, more complex molecule in the liquid state (C3H2OH(l)), a gaseous organic molecule (C2H5OH(g)), and two hydrogen atoms (2H(g)), we can typically predict that the gaseous organic molecule will have the highest entropy due its greater number of microstates and being in the gaseous state which allows particles to have the most freedom of motion. However, for this specific question - the substance CH₃OH(g) is not listed in the examples provided.
Examining the significant intermolecular forces is also useful, as substances with stronger intermolecular forces usually have lower entropy compared to those with weaker forces. Methanol (CH3OH) with its hydrogen bonding would be expected to have a lower entropy compared to an alkane of similar size due to stronger intermolecular attractions.