Final answer:
During phase changes from a solid to either a liquid or a gas (statement 1 and 2), energy must be absorbed by the substance. This energy is needed to overcome intermolecular forces and allow the atoms to separate from their tightly packed arrangement. The process of melting and sublimation are examples of phase changes where energy is gained.
Step-by-step explanation:
When a substance undergoes a phase change, the energy of its atoms and molecules is altered. There are different types of phase changes, such as melting, vaporization, and sublimation, each involving the transition to a more energetic state. For instance, during melting (solid to liquid) and vaporization (liquid to gas), energy is absorbed by the substance. This energy enables the atoms to move apart from each other by overcoming intermolecular forces, with solids requiring more energy to transition due to their stronger intermolecular forces.
Sublimation, the transition from solid directly to gas, also requires the input of energy. On the contrary, when a substance transitions from a more energetic state to a less energetic state, such as condensation (gas to liquid) or freezing (liquid to solid), energy is released. Hence, the relationship between energy and phase change is dependent on the direction of the change. Specifically for the student's question, statements 1 and 2 are correct as they involve gaining energy during the transitions from solid to liquid and solid to gas, respectively.