Question

Plaster of paris should be stored in a moisture proof container because:

• A. it absorbs moisture from the atmosphere and becomes hard
• B. it cannot be stored in plastic
• C. it will change its colour
• D. it will become soft

Answer 1

The correct option is A it absorbs moisture from the atmosphere and becomes hard

Plaster of paris is calcium sulphate and addition of water of crystallization to it leads to formation of gypsum which becomes hard material. It should be stored in water proof container.
${CaSO}_4\cdot \frac{1}{2}{H}_{2}O+\frac{3}{2}{H}_{2}O\to {CaSO}_4\cdot 2H_{2}O$