Question

The chemical substance used as a cast for setting broken bones in surgery is:

• A. Washing soda
• B. Plaster of Paris
• C. Quicklime
• D. Gypsum

Hint:

Plaster of Paris (\text{CaSO}_4 \cdot \frac{1}{2} H_2O) is used in orthopedic applications as it hardens upon mixing with water.

Answer 1

The Correct Option is B

Step 1: Understanding Plaster of Paris. Plaster of Paris (\text{CaSO}_4 \cdot \frac{1}{2} H_2O) is used in orthopedics for setting broken bones. When mixed with water, it hardens into solid gypsum. \[ \text{CaSO}_4 \cdot \frac{1}{2} H_2O + H_2O \rightarrow \text{CaSO}_4 \cdot 2H_2O \]
Step 2: Explanation of incorrect options.
- Washing soda (\text{Na}_2\text{CO}_3) is used in cleaning.
- Quicklime (\text{CaO}) is used in cement but not in bone setting.
- Gypsum (\text{CaSO}_4 \cdot 2H_2O) is a natural form of calcium sulfate but does not set like Plaster of Paris.