Question

which chemical waste situation should always be supervised or performed by an instructor? note that you still may need to alert your instructor about the described incident, even if you clean it up yourself select one cleaning up solid residue from a precipitation experiment cleaning up a broken beaker containing sodium chloride solution cleaning up solutions from a titration experiment cleaning up a broken mercury thermometer

Explanation:

Mercury is a highly toxic heavy - metal. Cleaning up a broken mercury thermometer requires special handling procedures to prevent mercury vapor exposure and environmental contamination. Instructors are trained to handle such hazardous waste situations properly. The other options involve relatively less hazardous materials and can often be cleaned up with proper training by students themselves.

Answer:

Cleaning up a broken mercury thermometer