Firefighter Skills and Hazardous Materials Test 2025 - Complete Practice Resource

Gypsum is the correct answer because it is a mineral that is often used in construction, particularly in drywall and plaster. While gypsum has some fire-resistant properties, it can lose integrity when exposed to high temperatures for extended periods. When heated, gypsum can begin to dehydrate and produce water vapor, which is a beneficial reaction up to a certain point, but prolonged exposure to intense heat can lead to significant weakening and eventual failure of the material.

In contrast, masonry, glass blocks, and concrete are generally more resilient to fire. Masonry materials, like brick and block, have high thermal mass and can withstand fire over extended durations without significant loss of structural integrity. Glass blocks are also capable of withstanding heat, making them suitable in fire-rated partition designs. Concrete is similarly heat resistant, and while it can spall or crack under extreme heat, it doesn’t lose its structural integrity as quickly as gypsum does. Thus, gypsum's limitations make it the material that does not hold up well against prolonged fire exposure.