Which statement best describes the difference between Flammable and Combustible liquids?

Which statement best describes the difference between Flammable and Combustible liquids?

• A. Combustibles ignite at a lower temperature
• B. Flammables ignite at a lower temperature
• C. They ignite at the same temperature
• D. Neither can ignite

Answer: (B)

The difference centers on the flash point: flammable liquids have lower flash points than combustible liquids. The flash point is the lowest temperature at which a liquid’s vapors can ignite in air. If a liquid has a low flash point, it can form ignitable vapors at relatively low temperatures, even near room temperature, which means it can ignite more readily when an ignition source is present. Flammable liquids typically have flash points below 100°F (37.8°C), so they pose ignition risks more easily in everyday conditions. Combustible liquids have flash points at or above 100°F, requiring higher heat to produce enough vapor to ignite. So the statement that flammables ignite at a lower temperature best captures the practical difference. The other options aren’t correct because combustible liquids do not ignite at lower temperatures, they don’t ignite at the same temperature, and it’s not true that neither can ignite.

The difference centers on the flash point: flammable liquids have lower flash points than combustible liquids. The flash point is the lowest temperature at which a liquid’s vapors can ignite in air. If a liquid has a low flash point, it can form ignitable vapors at relatively low temperatures, even near room temperature, which means it can ignite more readily when an ignition source is present. Flammable liquids typically have flash points below 100°F (37.8°C), so they pose ignition risks more easily in everyday conditions. Combustible liquids have flash points at or above 100°F, requiring higher heat to produce enough vapor to ignite. So the statement that flammables ignite at a lower temperature best captures the practical difference. The other options aren’t correct because combustible liquids do not ignite at lower temperatures, they don’t ignite at the same temperature, and it’s not true that neither can ignite.