Final answer:
The shut-off valve on gas hoses should be easily accessible and operable to ensure quick control of gas flow during emergencies or maintenance.
Step-by-step explanation:
On gas hoses, a shut-off valve should be installed so that it is easily accessible and operable. This is a safety consideration that ensures individuals can quickly and easily access the valve to control the gas flow in case of an emergency or for routine maintenance. When considering laboratory safety, it's important to know where specific safety equipment is located, such as the fire extinguisher and the eyewash station. The importance of managing gas flow in a controlled environment, underlining the role of a stopcock to either separate or allow gases, such as H₂ and O₂, to mix when opened. Such measures are critical in preventing accidents and ensuring the safe handling of potentially hazardous materials.