Which label indicates a material that may ignite without an external ignition source when exposed to air?

Which label indicates a material that may ignite without an external ignition source when exposed to air?

• A. Non-flammable compressed gas
• B. Radioactive substance
• C. Spontaneously Combustible
• D. Explosive

Answer: (C)

Spontaneous combustion is when a substance can heat up and catch fire in air without an external flame. Some materials oxidize on their own and generate heat fast enough to reach ignition temperature, so they can ignite by themselves if the heat isn’t released. The label Spontaneously Combustible warns handlers that the material may ignite without a spark or flame, so it needs careful storage and avoidance of heat, confinement, or contact with air in improper conditions. The other options don’t describe this self-ignition behavior. A non-flammable compressed gas is not prone to catch fire; a radioactive substance relates to radiation hazards; and an explosive involves a rapid energy release under specific triggers rather than ignition simply from exposure to air.

Spontaneous combustion is when a substance can heat up and catch fire in air without an external flame. Some materials oxidize on their own and generate heat fast enough to reach ignition temperature, so they can ignite by themselves if the heat isn’t released. The label Spontaneously Combustible warns handlers that the material may ignite without a spark or flame, so it needs careful storage and avoidance of heat, confinement, or contact with air in improper conditions.

The other options don’t describe this self-ignition behavior. A non-flammable compressed gas is not prone to catch fire; a radioactive substance relates to radiation hazards; and an explosive involves a rapid energy release under specific triggers rather than ignition simply from exposure to air.