Question

which is a precautionary measure? using a fire extinguisher to put out a flame wearing safety goggles while mixing chemicals

Explanation:

A precautionary measure is something done to prevent harm. Wearing safety goggles while mixing chemicals is a preventive action to avoid eye - injury from chemical splashes. Using a fire extinguisher to put out a flame is a reactive measure to an existing fire, not a precaution.

Answer:

wearing safety goggles while mixing chemicals