Final answer:
The triangle-shaped sticker on the barrel indicates that the barrel contains Hazardous materials. This symbol, known as a hazard diamond, provides valuable information about the dangers associated with the substances inside the barrel.
Step-by-step explanation:
The triangle-shaped sticker on the barrel indicates that the barrel contains Hazardous materials. This symbol, known as a hazard diamond, provides valuable information about the dangers associated with the substances inside the barrel. It is commonly used in laboratories and workplaces to ensure safety when handling chemicals.