Final answer:
A risk phrase from the given options is 'highly flammable,' indicating the potential danger of a substance igniting. It emphasizes the importance of following safety protocols and using proper precautions when handling flammable chemicals in a laboratory.
Step-by-step explanation:
The risk phrase that matches the options provided is: a) highly flammable. This is a designation used to indicate that a chemical substance can ignite under certain conditions, making it a higher risk in the laboratory setting. It is crucial to follow instructions carefully when dealing with flammable chemicals to avoid accidents such as fires or explosions, which can be caused by sparks, flames, or other heat sources.
Ensuring safety in the laboratory also involves wearing appropriate protective gear, such as goggles, and working in well-ventilated spaces to minimize inhalation of harmful fumes. Bunsen burners and other flame sources should be monitored closely to ensure that no flammable chemicals are in the vicinity, and that the flame is never left unattended. Long hair and loose clothing should be secured to prevent them from catching fire.