Which of the following carbonates do not give metal oxide on heating ?

Options

A. `CuCO_(3)`
B. `K_(2)CO_(3)`
C. `Na_(2)CO_(3)`
D. `MgCO_(3)`

Answer

To determine which of the following carbonates do not give metal oxide upon heating, we will analyze each option provided:

1. **Copper Carbonate (CuCO3)**:
- When heated, copper carbonate decomposes to form copper oxide (CuO) and carbon dioxide (CO2).
- **Reaction**:
\[ \text{CuCO}_3 \rightarrow \text{CuO} + \text{CO}_2 \]
- Conclusion: Copper carbonate gives a metal oxide upon heating. (Incorrect option)

2. **Potassium Carbonate (K2CO3)**:
- When heated, potassium carbonate does not decompose and no reaction occurs.
- Conclusion: Potassium carbonate does not give a metal oxide upon heating. (Correct option)

3. **Sodium Carbonate (Na2CO3)**:
- Similar to potassium carbonate, sodium carbonate also does not decompose upon heating, resulting in no reaction.
- Conclusion: Sodium carbonate does not give a metal oxide upon heating. (Correct option)

4. **Magnesium Carbonate (MgCO3)**:
- When heated, magnesium carbonate decomposes to form magnesium oxide (MgO) and carbon dioxide (CO2).
- **Reaction**:
\[ \text{MgCO}_3 \rightarrow \text{MgO} + \text{CO}_2 \]
- Conclusion: Magnesium carbonate gives a metal oxide upon heating. (Incorrect option)

### Final Conclusion:
The carbonates that do not give metal oxide upon heating are **Potassium Carbonate (K2CO3)** and **Sodium Carbonate (Na2CO3)**.