The diagram below represents a phase change.
Which of the following best describes what is happening in the diagram?
A.
A liquid is changing into a gas because pressure in the system is increasing.
B.
A gas is changing into a liquid because thermal energy is being added to the system.
C.
A gas is changing into a liquid because thermal energy is being removed from the system.
D.
A liquid is changing into a gas because pressure in the system is decreasing.
No diagram.
C. A gas is changing into a liquid because thermal energy is being removed from the system.
To determine the answer to this question, we need to analyze the information and concepts related to phase changes.
In the diagram, there is a substance moving from a gaseous state to a liquid state. This means that a gas is changing into a liquid. Now, let's look at the options provided.
Option A states that a liquid is changing into a gas because pressure in the system is increasing. This is not correct, as we can see in the diagram that the substance is condensing, which implies a transition from gas to liquid.
Option B states that a gas is changing into a liquid because thermal energy is being added to the system. This is also incorrect. When thermal energy is added to a substance, it usually leads to an increase in temperature and often causes a phase change from solid to liquid or liquid to gas, not the other way around as shown in the diagram.
Option C states that a gas is changing into a liquid because thermal energy is being removed from the system. This is the correct answer. When thermal energy is removed from a gas, it loses kinetic energy, causing its particles to slow down and come closer together, leading to condensation and a transition to the liquid state.
Option D states that a liquid is changing into a gas because pressure in the system is decreasing. This is not correct because the diagram clearly shows the opposite situation, where a gas is changing into a liquid.
Therefore, the correct answer is C. A gas is changing into a liquid because thermal energy is being removed from the system.