Final answer:
A precipitate that changes color upon exposure to sunlight has undergone a chemical change, as it indicates the formation of a new substance with different properties.
Step-by-step explanation:
The question about whether a precipitate exposed to sunlight has undergone a chemical change or physical change can be addressed by considering the evidence. When a precipitate forms and undergoes a color change from colorless to yellow in the presence of sunlight, it is indicative of a chemical change. This is because a new substance has likely been formed with different properties than the original substances involved.
Factors such as change in color, temperature change, light emission, formation of bubbles, and formation of precipitates are strong indicators of chemical changes. In contrast, physical changes involve changes in the state or appearance of a substance without altering its molecular composition, such as ice melting or water boiling.
Therefore, if the precipitation in question changed color upon exposure to sunlight, a chemical change has occurred because the substance's identity has been altered.