Which material is fire resistant and used for gypsum plaster wallboard?

• A. Gypsum
• B. Cement
• C. Wood
• D. Sand

Answer: (A)

The main idea is that gypsum provides fire resistance in drywall. Gypsum, or calcium sulfate dihydrate, forms the core of gypsum plaster wallboard and is surrounded by paper faces. When exposed to heat, gypsum undergoes endothermic dehydration, releasing bound water as steam. This process absorbs a lot of heat and slows the temperature rise, helping the board resist fire for a period and buy time for occupants and rescue operations.

Other materials listed don’t fit the purpose: cement boards exist but they’re not gypsum plaster wallboard; wood is combustible and would fuel a fire; sand isn’t used as the core of gypsum plaster wallboard.