On heating alkali metal nitrated product formed are (except `LiNO_3`)

Options

A. `NO_2 and O_2` only
B. `NO_2` only
C. `NO_2` and MO only
D. `MNO_2 and O_2`

Answer

To solve the question regarding the products formed when heating alkali metal nitrates (except LiNO3), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Alkali Metal Nitrates**:
The alkali metal nitrates we are considering are NaNO3, KNO3, RbNO3, and CsNO3, since we are excluding LiNO3.

2. **Understand the Decomposition Reaction**:
When alkali metal nitrates are heated, they undergo thermal decomposition. The general reaction for the decomposition of an alkali metal nitrate (MNO3) can be represented as:
\[ 2 \text{MNO}_3 \rightarrow 2 \text{MNO}_2 + \text{O}_2 \]
Here, M represents the alkali metal (Na, K, Rb, Cs).

3. **Write the Specific Reactions**:
- For Sodium Nitrate (NaNO3):
\[ 2 \text{NaNO}_3 \rightarrow 2 \text{NaNO}_2 + \text{O}_2 \]
- For Potassium Nitrate (KNO3):
\[ 2 \text{KNO}_3 \rightarrow 2 \text{KNO}_2 + \text{O}_2 \]
- For Rubidium Nitrate (RbNO3):
\[ 2 \text{RbNO}_3 \rightarrow 2 \text{RbNO}_2 + \text{O}_2 \]
- For Cesium Nitrate (CsNO3):
\[ 2 \text{CsNO}_3 \rightarrow 2 \text{CsNO}_2 + \text{O}_2 \]

4. **Generalize the Products**:
From the reactions above, we can see that for all alkali metal nitrates (except LiNO3), the products formed upon heating are:
- Alkali metal nitrite (MNO2)
- Oxygen gas (O2)

5. **Conclusion**:
Therefore, the products formed when heating alkali metal nitrates (except LiNO3) are MNO2 and O2. The correct answer from the options provided is:
- **MNO2 and O2**

### Final Answer:
The products formed on heating alkali metal nitrates (except LiNO3) are MNO2 and O2.