What form of latent heat is responsible for changing propane from liquid to gas?

The correct answer is vaporization. This process specifically refers to the change of a substance from a liquid state to a gaseous state, which is precisely what occurs when propane transitions from liquid to gas. During vaporization, latent heat is absorbed, allowing the liquid propane molecules to gain enough energy to overcome intermolecular forces and enter the gas phase.

In the context of propane, when it is subjected to the right conditions, such as changes in temperature or pressure, it requires heat energy to facilitate this transformation from liquid to gas. This energy is absorbed without causing a change in temperature initially, hence the term 'latent heat'—heat that is hidden within the phase change.

Other processes like condensation involve the transition from gas to liquid, melting refers to the change from solid to liquid, and freezing is the process of changing from liquid to solid. These are distinct phase changes that do not apply to the transition of propane from liquid to gas, further clarifying why vaporization is the correct and relevant choice in this context.