Which material is classified as a flammable solid?

Magnesium powder is classified as a flammable solid because it can ignite and burn when it is exposed to air or heat, particularly in fine particulate form. The powder has a lower ignition temperature compared to larger chunks of magnesium, making it a significant fire hazard. When magnesium burns, it produces a bright white flame and generates substantial heat, which can exacerbate the risk of fire spread, especially in environments where flammable materials are present.

In contrast, other materials listed—like aluminum, wood shavings, and iron filings—while they may be combustible, do not meet the criteria for flammable solids in the same way that magnesium powder does under specific conditions. For instance, wood shavings are typically categorized as combustible materials rather than specifically flammable solids. Iron filings, although they can be hazardous under certain circumstances, do not exhibit the same level of reactivity and flammability as magnesium powder.