Which physical state might a substance with a simple molecular structure be in at room temperature?

A substance with a simple molecular structure is likely to exist as a liquid or gas at room temperature because these substances typically consist of small, covalently bonded molecules. The intermolecular forces in such compounds, often weak van der Waals forces or dipole-dipole interactions, allow them to be easily overcome at moderate temperatures. As a result, many simple molecular substances, such as water and carbon dioxide, can exist in liquid or gaseous states under standard conditions.

In contrast, substances with strong ionic or covalent networks tend to be solids at room temperature due to the strong forces holding their structure together. Plasma, being an ionized state of matter usually found at very high temperatures (like in stars), is not relevant in this context. The option "None of the above" does not apply since there are substances that fit the criteria of existing as liquids or gases among simple molecular structures.