Which of the following methods can cause a substance to change from a solid to a liquid or from a liquid to a gas?

• A. Increasing the temperature of the substance
• B. Exposing the substance to ultraviolet light
• C. Decreasing the temperature of the substance
• D. Adding a catalyst to the substance

Answer: (A)

Verified step by step guidance

1. Understand the phase changes involved: solid to liquid is melting, and liquid to gas is vaporization (boiling or evaporation).
2. Recall that phase changes from solid to liquid or liquid to gas require energy input to overcome intermolecular forces.
3. Recognize that increasing the temperature of a substance adds thermal energy, which can provide the energy needed for these phase changes.
4. Note that decreasing the temperature removes energy, which typically causes phase changes in the opposite direction (e.g., liquid to solid or gas to liquid).
5. Understand that adding a catalyst or exposing the substance to ultraviolet light does not directly provide the thermal energy required for melting or vaporization.