What hazard class is indicated by a placard with a white diamond, skull and crossbones at the top, and the number 2 at the bottom?

The placard described features a white diamond shape, a skull and crossbones symbol at the top, and the number 2 at the bottom. This specific design is consistent with the identification of hazardous materials associated with poison or toxic substances, specifically poisonous gases.

The skull and crossbones symbol is widely recognized as a sign of danger, particularly regarding lethal substances that can cause harm through inhalation, ingestion, or skin contact. The number 2 indicates the level of toxicity associated with the material, often referring to the classification of the hazard.

In this case, the presence of a white diamond shape is not generally used for flammable materials, explosives, or corrosive substances, which typically utilize different color schemes and symbols to denote their respective hazards. Therefore, this placard accurately represents poisonous gas as outlined by the specific characteristics of the symbol and the coloring involved.