A : `CaCO_(3)` requires more temperature than `MgCO_(3)` for decomposition.
R : Group II metal carbonates on decomposition gives respective oxide and `CO_(2)`

Options

A. If both Assertion & Reason are true and the reason is the correct explanantion of the assertion, then mark (1).
B. If both Assertion & Reason are true and the reason is the correct explanantion of the assertion, then mark (2).
C. If Assertion is true statement but Reason is false. Them mark (3).
D. If both Assertion and reason are false statement, then mark (4).

Answer

To solve the problem, we need to analyze the assertion and reason given in the question step by step.

### Step 1: Analyze the Assertion
The assertion states that "CaCO₃ requires more temperature than MgCO₃ for decomposition."

- **Decomposition of Carbonates**: When metal carbonates decompose, they form metal oxides and carbon dioxide.
- **Reactions**:
- For Calcium Carbonate:
\[ \text{CaCO}_3 \rightarrow \text{CaO} + \text{CO}_2 \]
- For Magnesium Carbonate:
\[ \text{MgCO}_3 \rightarrow \text{MgO} + \text{CO}_2 \]

### Step 2: Compare the Stability of Carbonates
The stability of metal carbonates generally decreases down the group in the periodic table.

- **Group II Carbonates**: As we move down the group from magnesium to calcium, the size of the metal ion increases, and the electropositive character increases. This leads to a stronger bond between the carbonate ion and the metal ion in calcium carbonate compared to magnesium carbonate.
- **Bond Strength**: The bond strength in CaCO₃ is greater than that in MgCO₃ due to the higher electropositive character of calcium compared to magnesium.

### Step 3: Conclusion for Assertion
Since CaCO₃ has a stronger bond and is more stable than MgCO₃, it requires more energy (higher temperature) to decompose. Therefore, the assertion is **true**.

### Step 4: Analyze the Reason
The reason states that "Group II metal carbonates on decomposition give respective oxide and CO₂."

- This statement is generally true as it describes the decomposition products of group II metal carbonates.

### Step 5: Check if the Reason Explains the Assertion
While the reason is true, it does not explain why CaCO₃ requires more temperature than MgCO₃ for decomposition. The reason simply states the products of decomposition without addressing the energy required for the decomposition process.

### Final Conclusion
- **Assertion**: True
- **Reason**: True, but does not explain the assertion.

### Answer Options
Based on the analysis, the correct option is:
- **Option 2**: Both assertion and reason are true, but the reason is not the correct explanation of the assertion.