Dead burnt plaster is

Options

A. `CasO_4 .2H_2O`
B. `CasO_4.(1/2)H_2O`
C. `CaSO_3`
D. `CaSO_4`

Answer

**Step-by-Step Solution:**

1. **Understanding the Term "Dead Burn Plaster":**
- Dead burnt plaster is a term used to describe a specific form of calcium sulfate.

2. **Chemical Composition:**
- The chemical formula for dead burnt plaster is anhydrous calcium sulfate, which is represented as CaSO₄.

3. **Formation Process:**
- Dead burnt plaster is produced by heating gypsum (calcium sulfate dihydrate, CaSO₄·2H₂O) at high temperatures. During this process, the water molecules present in gypsum are removed.

4. **Chemical Reaction:**
- The reaction can be summarized as follows:
\[ \text{CaSO}_4 \cdot 2\text{H}_2\text{O} \xrightarrow{\text{heat}} \text{CaSO}_4 + 2\text{H}_2\text{O} \]
- Here, gypsum loses its water molecules upon heating, resulting in the formation of anhydrous calcium sulfate.

5. **Conclusion:**
- Therefore, dead burnt plaster is essentially anhydrous calcium sulfate (CaSO₄) that is formed after the removal of water from gypsum.

**Final Answer:**
Dead burnt plaster is anhydrous calcium sulfate (CaSO₄).

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