What can be inferred about a molecule with high molecular weight and low vapor pressure?

• A. It is likely to be a gas at room temperature
• B. It is likely to be a liquid or solid at room temperature
• C. It is reactive under standard conditions
• D. It has high volatility

Answer: (B)

A molecule with high molecular weight and low vapor pressure is likely to be a liquid or solid at room temperature because these characteristics generally indicate stronger intermolecular forces.

Molecules with high molecular weights tend to have larger, more complex structures, which often leads to increased London dispersion forces (a type of van der Waals force) and sometimes dipole-dipole interactions. These stronger intermolecular attractions mean that more energy is required to overcome these forces and convert the substance into a gas, contributing to the low vapor pressure observed.

Additionally, a low vapor pressure is typically associated with a lower tendency to escape into the gaseous state. Thus, for a substance with such properties, it is more stable in the liquid or solid phase at room temperature than as a vapor.

This understanding also helps indicate that the other options do not align with these characteristics. A gas at room temperature would typically exhibit low molecular weight and high vapor pressure due to its high volatility, which contradicts the properties of the molecule described in the question. Reactivity can vary widely and is not solely determined by molecular weight or vapor pressure. High volatility is directly opposite to the low vapor pressure, affirming that the correct inference is that the molecule is likely to be a liquid or solid at