Final answer:
An exposed urine sample to room light for over 2 hours will most likely experience a loss of color due to photodegradation of urochrome.
Step-by-step explanation:
When a urine sample is exposed to room light for an extended period, such as over 2 hours, the most likely change would be a loss of color. Urine contains a yellow pigment called urochrome, which is responsible for its typical color. However, when left in light, the urine can undergo photodegradation, where light energy breaks down the pigments causing the urine to lose its color. Additionally, bacteria present in the urine can convert urea to ammonia, especially in a warm environment, but this typically requires more time and may not occur solely due to light exposure within two hours.