Which of the following factors can cause a substance to transition between the liquid and gas states on a phase diagram?

• A. Decreasing both temperature and pressure
• B. Increasing temperature or decreasing pressure
• C. Decreasing temperature and increasing pressure
• D. Increasing both temperature and pressure

Answer: (B)

Verified step by step guidance

1. Understand that a phase diagram shows the states of a substance (solid, liquid, gas) under different conditions of temperature and pressure.
2. Recall that to transition from liquid to gas (vaporization), the substance must gain enough energy, which typically happens by increasing temperature or decreasing pressure.
3. Recognize that increasing temperature provides the molecules with more kinetic energy to overcome intermolecular forces, leading to vaporization.
4. Understand that decreasing pressure lowers the external force on the liquid, making it easier for molecules to escape into the gas phase.
5. Conclude that the correct factors causing a transition between liquid and gas are increasing temperature or decreasing pressure, as these move the system across the liquid-gas boundary on the phase diagram.