Which hazardous waste characteristic can indicate a substance is reactive?

The characteristic that indicates a substance is reactive is its ability to undergo violent chemical reactions. Reactive waste can pose significant risks because it can potentially react violently when mixed with other substances, change temperature rapidly, or generate toxic gases or fumes. This reactivity makes it necessary to handle and store such materials with caution, as they can lead to hazardous situations, including explosions or the release of harmful substances into the environment.

For example, certain chemicals might react explosively when they come into contact with water or air. Therefore, identifying a substance as reactive is crucial for ensuring safety in handling and disposal practices. The other characteristics listed do not inherently indicate reactivity. A high boiling point, ease of biodegradability, or solid form don't provide information on the potential for violent chemical reactions.