Lime stone is:-

Options

A. `CaO`
B. `Ca(OH)_(2)`
C. 1 & 2 both
D. None of the above

Answer

To solve the question "Limestone is:-", we need to identify the correct chemical composition of limestone from the given options: calcium oxide (CaO), calcium hydroxide (Ca(OH)₂), both 1 and 2, or none of the above.

### Step-by-Step Solution:

1. **Identify the Chemical Formula of Limestone**:
- Limestone is primarily composed of calcium carbonate, which has the chemical formula CaCO₃.

2. **Evaluate the Given Options**:
- **Option 1**: Calcium oxide (CaO) - This is not limestone; it is known as quick lime.
- **Option 2**: Calcium hydroxide (Ca(OH)₂) - This is not limestone; it is known as slaked lime.
- **Option 3**: Both 1 and 2 - Since neither CaO nor Ca(OH)₂ is limestone, this option is incorrect.
- **Option 4**: None of the above - This option suggests that limestone is not represented by any of the previous options.

3. **Conclusion**:
- Since limestone is calcium carbonate (CaCO₃) and none of the options provided (CaO, Ca(OH)₂, both) represent limestone, the correct answer is **none of the above**.

### Final Answer:
Limestone is **none of the above**.

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