Question

Plaster of Paris is obtained by heating gypsum at:

• A. \(0^\circ C\)
• B. \(200^\circ C\)
• C. \(50^\circ C\)
• D. \(100^\circ C\)

Hint:

Remember: \[ \text{Gypsum} \xrightarrow{100^\circ C} \text{Plaster of Paris} \] Formulas: \[ \text{Gypsum} = CaSO_4 \cdot 2H_2O \] \[ \text{POP} = CaSO_4 \cdot \frac{1}{2}H_2O \]

Answer 1

The Correct Option is D

Concept:
Plaster of Paris is prepared from gypsum. Gypsum is: \[ CaSO_4 \cdot 2H_2O \] When gypsum is heated to about: \[ 100^\circ C \] it loses water molecules and forms Plaster of Paris. Reaction: \[ CaSO_4 \cdot 2H_2O \rightarrow CaSO_4 \cdot \frac{1}{2}H_2O + \frac{3}{2}H_2O \]

Step 1: Identify the raw material.
Gypsum is hydrated calcium sulphate. Formula: \[ CaSO_4 \cdot 2H_2O \]

Step 2: Understand preparation of Plaster of Paris.
On heating gypsum around: \[ 100^\circ C \] partial removal of water occurs and Plaster of Paris forms.

Step 3: Examine options carefully.
Option (A): \(0^\circ C\)
No heating. Incorrect. Option (B): \(200^\circ C\)
Too high. Incorrect. Option (C): \(50^\circ C\)
Insufficient heating. Incorrect. Option (D): \(100^\circ C\)
Correct temperature. Correct.

Step 4: Select the correct answer.
Therefore, Plaster of Paris is obtained by heating gypsum at: \[ \boxed{100^\circ C} \] Hence, \[ \boxed{(4)\ 100^\circ C} \]