Dead burnt plaster is

Options

A. `CaSO_(4)`
B. `CaSO_(4)*(1)/(2)H_(2)O`
C. `CaSO_(4)*H_(2)O`
D. `CaSO_(4)*2H_(2)O`

Answer

**Step-by-Step Solution:**

1. **Understanding the Terms**:
- The term "dead burnt plaster" refers to a specific form of calcium sulfate that is produced when plaster of Paris (POP) is heated.

2. **Identifying Plaster of Paris**:
- Plaster of Paris is chemically represented as calcium sulfate hemihydrate, which has the formula CaSO₄·½H₂O.

3. **Heating Plaster of Paris**:
- When plaster of Paris is heated, it loses its water of crystallization and converts into anhydrous calcium sulfate.

4. **Chemical Formula of Dead Burnt Plaster**:
- The anhydrous form of calcium sulfate is represented as CaSO₄. This is the chemical formula for dead burnt plaster.

5. **Analyzing the Options**:
- A) Calcium sulfate (CaSO₄) - This is the correct answer as it represents the anhydrous form.
- B) Calcium sulfate with half water of crystallization (CaSO₄·½H₂O) - This is the formula for plaster of Paris, not dead burnt plaster.
- C) Calcium sulfate with one water of crystallization (CaSO₄·H₂O) - This is incorrect for dead burnt plaster.
- D) Calcium sulfate with two waters of crystallization (CaSO₄·2H₂O) - This is also incorrect for dead burnt plaster.

6. **Conclusion**:
- Therefore, the correct answer is option A: Calcium sulfate (CaSO₄).

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