1. Which of the following happens when a material undergoes a phase change?
(a) The temperature changes.
(b) The chemical composition changes.
(c) Heat flows into or out of the material.
(d) The molecules break apart into atoms.
2. As heat is added to water, is it possible for the temperature measured by a thermometer in the water to remain constant?
(a) Yes, the water could be changing phase.
(b) No, adding heat will always change the temperature.
(c) Maybe; it depends on the rate at which the heat is added.
(d) Maybe; it depends on the initial water temperature.