The chemical composition of limestone is

Options

A. calcium carbonate
B. calcium oxide
C. calcium hydroxide
D. calcium sulphate

Explanation

**Step-by-Step Solution:**

1. **Identify the Question**: The question asks for the chemical composition of limestone.

2. **Recall the Chemical Formula**: Limestone is commonly known to have the chemical formula CaCO3.

3. **Break Down the Formula**:
- Ca stands for Calcium.
- CO3 represents the Carbonate group, which consists of one carbon atom and three oxygen atoms.

4. **Combine the Information**: Therefore, the chemical composition of limestone can be described as Calcium Carbonate.

5. **Evaluate the Options**:
- Option A: Calcium Carbonate (CaCO3) - This is correct.
- Option B: Calcium Oxide (CaO) - This is incorrect as it does not contain carbon.
- Option C: Calcium Hydroxide (Ca(OH)2) - This is incorrect as it contains the hydroxide group (OH), which is not present in limestone.
- Option D: Calcium Sulphate (CaSO4) - This is incorrect as it contains sulphate (SO4), which is not present in limestone.

6. **Conclusion**: The correct answer is Option A: Calcium Carbonate.

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