Which of the following compound on heating does not produce metal oxide?

Options

A. `MgCl_(2)*6H_(2)O`
B. `K_(2)Cr_(2)O_(7)`
C. `K_(2)CO_(3)`
D. `Cu(NO_(3))_(2)`

Explanation

To determine which of the given compounds does not produce a metal oxide upon heating, we will analyze each compound step by step.

### Step 1: Analyze MgCl2·6H2O
- When magnesium chloride hexahydrate (MgCl2·6H2O) is heated, it decomposes to form magnesium oxide (MgO), hydrochloric acid (HCl), and water (H2O).
- **Reaction**:
\[ \text{MgCl}_2 \cdot 6\text{H}_2\text{O} \rightarrow \text{MgO} + 2\text{HCl} + 5\text{H}_2\text{O} \]
- **Conclusion**: This produces a metal oxide (MgO).

### Step 2: Analyze K2Cr2O7
- When potassium dichromate (K2Cr2O7) is heated, it decomposes to form potassium chromate (K2CrO4), chromium(III) oxide (Cr2O3), and oxygen gas (O2).
- **Reaction**:
\[ \text{K}_2\text{Cr}_2\text{O}_7 \rightarrow \text{K}_2\text{CrO}_4 + \text{Cr}_2\text{O}_3 + \frac{3}{2}\text{O}_2 \]
- **Conclusion**: This produces metal oxides (Cr2O3).

### Step 3: Analyze K2CO3
- When potassium carbonate (K2CO3) is heated, it does not decompose further; instead, it melts without producing any metal oxide.
- **Conclusion**: This does not produce a metal oxide.

### Step 4: Analyze Cu(NO3)2
- When copper(II) nitrate (Cu(NO3)2) is heated, it decomposes to form copper(II) oxide (CuO), nitrogen dioxide (NO2), and oxygen gas (O2).
- **Reaction**:
\[ \text{Cu(NO}_3\text{)}_2 \rightarrow \text{CuO} + 2\text{NO}_2 + \text{O}_2 \]
- **Conclusion**: This produces a metal oxide (CuO).

### Final Conclusion
After analyzing all four compounds, we find that the only compound that does not produce a metal oxide upon heating is **K2CO3**.

### Answer: K2CO3

---