American Chemical Society (ACS) Laboratory Safety Practice Test

The option indicating the failure of a belt-driven roof-mounted hood motor aligns with the concept of the lowest possible airflow. When a hood motor fails, it typically results in an inability to move air effectively, which means that the airflow would drop significantly, potentially reaching the lowest levels. This diminished airflow can lead to inadequate capture of fumes and vapors in a laboratory setting, compromising safety and ventilation.

In contrast, excessive airflow would suggest that the hood is functioning correctly or even operating at higher than normal efficiency, which is not indicative of a motor failure. Instantaneous airflow does not speak to the performance over time, and could imply fluctuating performance rather than outright failure. Consistent airflow would imply that the system is operating as intended, allowing for proper ventilation and safety during laboratory processes. Therefore, the condition associated with a failing motor is accurately represented by the lowest possible airflow.