True or False: Vapor pressures of a substance at 100°F are always higher than at 68°F.

• A. True
• B. False
• C. It depends on the substance
• D. Only for liquids

Answer: (A)

The correct response is that vapor pressures of a substance at 100°F are generally higher than at 68°F. This understanding relies on the relationship between temperature and vapor pressure. As the temperature of a substance increases, the kinetic energy of its molecules also rises, leading to a greater tendency for those molecules to escape into the vapor phase. Consequently, the vapor pressure—the pressure exerted by the vapor when it is in equilibrium with its liquid or solid form—increases with rising temperature.

The exception would be substances that behave unusually under specific conditions, but as a general rule, for most liquids and some solids, this relationship holds true. Therefore, the statement aligns with fundamental principles of vapor pressure and temperature interactions.