Which of the following is NOT a use of plaster of Paris? (i) Manufacture of glass, soap and paper (ii) used in plaster for supporting fractured bones. (iii) making toys, materials for decoration and for making surfaces smooth. (iv) Used in chemistry laboratories for sealing air gaps in apparatus where air tight arrangement is required.

Correct option is D

Correct Answer: D Only i
Explanation:
Plaster of Paris (POP) is widely used in construction, medical applications, and artistic purposes. However, it is not used in the manufacture of glass, soap, and paper. Instead, materials like limestone (CaCO₃) and sodium carbonate (Na₂CO₃) are commonly used in these industries.
Uses of Plaster of Paris (POP):

• Medical Applications: POP is used for making plaster casts to support fractured bones.
  
•  Decoration & Art: It is used in making toys, statues, and decorative materials.
  
•  Construction: It is used for coating walls and ceilings to make them smooth.
  
•  Chemistry Laboratories: It is used to seal air gaps in apparatus for air-tight experiments.
  Since statement (i) is incorrect, the correct answer is option D (Only i).

Information Booster:

• Chemical Formula of Plaster of Paris: CaSO₄·½H₂O (Calcium Sulphate Hemihydrate)
  
•  Preparation: POP is obtained by heating gypsum (CaSO₄·2H₂O) at 373K (about 150°C).
  
• Setting Process: When mixed with water, POP reabsorbs water and hardens into gypsum.
  
•  Uses in Dentistry: It is used in moulds for dental impressions.
  
•  POP should be stored in air-tight containers to prevent it from reacting with moisture and forming hard lumps.