2025 · Q96
Which one among the following statements regarding gypsum is not correct?
general-sciencechemistry
- AOn heating gypsum at 373 K, it loses water molecules and becomes CaSO₄·H₂O.
- BOn mixing with water, plaster of Paris changes to gypsum.
- CPlaster of Paris is used for supporting fractured bones.
- DAlthough gypsum possesses water of crystallization, it is not a liquid at room temperature.
Explanation
Heating gypsum (CaSO4.2H2O) at 373 K yields plaster of Paris, which is the hemihydrate CaSO4.1/2H2O — not the monohydrate CaSO4.H2O — so statement A is not correct. Plaster of Paris does revert to gypsum on mixing with water, it is used for supporting fractured bones, and gypsum, though hydrated, is a solid at room temperature. Hence A is the not-correct statement.