Which of the following best describes the molecular changes that occur when ice cream melts and becomes a liquid?

• A. The molecules gain energy and move more freely, breaking the rigid structure of the solid.
• B. The molecules are converted into gas and disperse into the air.
• C. The molecules lose energy and form stronger bonds, creating a more ordered structure.
• D. The chemical composition of the molecules changes, forming new substances.

Answer: (A)

Verified step by step guidance

1. Understand the physical process of melting: when a solid like ice cream melts, it changes from a solid state to a liquid state without changing its chemical composition.
2. Recall that in a solid, molecules are arranged in a fixed, rigid structure and have limited movement, mainly vibrating in place.
3. During melting, molecules absorb energy (heat), which increases their kinetic energy, allowing them to overcome some of the forces holding them in the rigid solid structure.
4. As a result, the molecules move more freely and slide past each other, transitioning into the liquid phase where the structure is less ordered but the molecules remain close together.
5. Recognize that melting does not involve molecules turning into gas, losing energy to form stronger bonds, or changing their chemical composition; it is a physical change involving increased molecular motion and breaking of the solid's rigid structure.