Which statement describes Class 5 oxidizing substances?

• A. They are always non-reactive.
• B. They are always explosive.
• C. They do not react to heat.
• D. They support its own combustion through using oxygen.

Answer: (D)

Oxidizing substances in Class 5 promote combustion by supplying oxygen to fuel burning. They enable other materials to ignite and burn more readily because they release oxygen or make oxidation easier. This is why describing them as those that support combustion using oxygen best captures their role: they drive the burning of other substances, not necessarily their own independent combustion. They are not inherently non-reactive, and they are not always explosive—some oxidizers can be stable, while others can react violently under the right conditions. Heating many oxidizers can trigger decomposition or rapid oxygen release, which is why heat can make fires worse. For example, an oxidizer like a nitrate releases oxygen when heated, helping nearby fuels burn more vigorously.