Which of the following substances is considered an ordinary combustible?

An ordinary combustible is defined as a material that burns easily and is commonly found in structures, such as wood, cloth, and paper. Paper is a classic example of an ordinary combustible, as it ignites easily and can sustain combustion under normal fire conditions. The cellulose fibers in paper allow it to burn rapidly when exposed to an ignition source.

In contrast, gasoline and magnesium are not classified as ordinary combustibles. Gasoline is a flammable liquid that requires careful handling due to its ability to ignite easily and vigorously at relatively low temperatures; it is categorized differently because of its physical state and the nature of its combustion. Electrical wiring involves insulated materials and does not readily ignite in the same way as ordinary combustibles, thus falling under a different classification. Magnesium, while it can burn, requires a higher temperature to ignite and burns at a much higher rate, making it categorized as a metal fire hazard rather than an ordinary combustible.

Understanding these distinctions helps in identifying fire hazards and taking appropriate safety precautions in environments where different materials are present.