Question

Setting of plaster of paris involves:

• A. Oxidation with atmospheric oxygen
• B. Combination with atmospheric $C{O}_2$
• C. Dehydration
• D. Hydration to yield another hydrate

Answer 1

The correct option is D Hydration to yield another hydrate

On hydration of Plaster of Paris, it converts into Gypsum.
$\underset{\text{Plaster of Paris}}{CaS{O}_4.\frac{1}{2}{H}_{2}O}+\frac{3}{2}{H}_{2}O\to \underset{\text{Gypsum}}{CaS{O}_4.2H_{2}O}$