Consider the below statements and identify the correct answer.

Statement-I: Plaster of Paris has a very remarkable property of setting into hard mass on wetting with water.

Statement-II: Plaster of Paris is used in chemistry laboratories for sealing air gaps in apparatus where air tight arrangement is required.

Question

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RRB Group D 29 Aug 2022 Shift 2 Official Paper

Answer 1

The correct answer Both the statements are true.

Key Points:

Plaster of Paris's characteristics:
- When wetted with water or exposed to a mixture and left to dry, it solidifies into a hard mass.
- The substance is a fine white powder.
Applications:
- In order to assure proper healing, it is used in hospitals to fix broken bones.
- Due to its setting property, it is used to make toys, decorative items, inexpensive ornaments, cosmetics, blackboard chalk, and statue casts.
- It serves as a fire-retardant substance.
- It is used in chemistry labs to close air gaps in equipment when an airtight arrangement is necessary.

Additional Information:

Calcium sulphate hemihydrate is what makes plaster of Paris (calcium sulphate half-hydrate).
CaSO₄.12H₂O is the plaster of Paris's chemical formula.
Gypsum (CaSO4.2H2O) is heated to a temperature of 100 °C to prepare it.
Gypsum loses three-fourths of its water of crystallization when heated to a temperature of 100°C (373K), creating Plaster of Paris.