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 will go through the following steps:

### Step 1: Identify the Chemical Formula of Limestone
Limestone is primarily composed of calcium carbonate, which has the chemical formula \( \text{CaCO}_3 \).

### Step 2: Analyze the Given Options
The options provided are:
- Option A: Calcium oxide (\( \text{CaO} \))
- Option B: Calcium hydroxide (\( \text{Ca(OH)}_2 \))
- Option C: 1 and 2 both
- Option D: None of the above

### Step 3: Compare Limestone with the Options
- **Calcium oxide (\( \text{CaO} \))** is also known as quick lime, which is produced when limestone is heated.
- **Calcium hydroxide (\( \text{Ca(OH)}_2 \))** is known as slaked lime and is produced when quick lime is mixed with water.

### Step 4: Determine the Correct Answer
Since limestone is \( \text{CaCO}_3 \) and neither calcium oxide nor calcium hydroxide matches this formula, the correct answer is:
- **Option D: None of the above.**

### Step 5: Explanation of the Interconnection
- When limestone (\( \text{CaCO}_3 \)) is heated, it decomposes into calcium oxide (\( \text{CaO} \)) and carbon dioxide (\( \text{CO}_2 \)).
- When water is added to calcium oxide, it forms calcium hydroxide (\( \text{Ca(OH)}_2 \)).
- Thus, limestone is distinct from both calcium oxide and calcium hydroxide.

### Final Answer
The correct answer is **Option D: None of the above.**

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