Final answer:
When a substance loses thermal energy, the two changes of state that can occur are condensation (gas to liquid) and freezing (liquid to solid).
Step-by-step explanation:
The question refers to the changes of state that occur when a substance loses thermal energy. When a substance loses thermal energy, it undergoes a transition to a less energetic state. These changes are:
- Condensation: which is the change from a gas to a liquid.
- Freezing: which is the change from a liquid to a solid.
There are other changes of state that occur without thermal energy loss such as sublimation (solid to gas) and deposition (gas to solid).
However, the two changes of state that specifically involve the loss of thermal energy are condensation and freezing. Sublimation and deposition do occur under certain conditions but do not typically involve the loss of thermal energy, as sublimation is an isothermal process and deposition is simply the reverse of sublimation.