Respuesta :
Reason number 1 (before) is that you could contaminate your samples if you have foreign material on your hands.
Reason number 2 (after) is that you could spread/or ingest dangerous chemicals or substances that you have handled in the lab.
Reason number 2 (after) is that you could spread/or ingest dangerous chemicals or substances that you have handled in the lab.
1. You dont want to digest possible dangerous chrmicals
2. Your hands could be durty and contaminate the experiment
2. Your hands could be durty and contaminate the experiment