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 metals include Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), and Francium (Fr). However, we are excluding Lithium nitrate (LiNO3) from our consideration.

2. **Write the General Reaction for Heating Alkali Metal Nitrates**:
The general decomposition reaction for alkali metal nitrates (MNO3) when heated can be represented as:
\[ 2MNO_3 \rightarrow 2MNO_2 + O_2 \]
where M represents the alkali metal (Na, K, Rb, Cs, Fr).

3. **Decompose Each Alkali Metal Nitrate**:
- For Sodium Nitrate (NaNO3):
\[ 2NaNO_3 \rightarrow 2NaNO_2 + O_2 \]
- For Potassium Nitrate (KNO3):
\[ 2KNO_3 \rightarrow 2KNO_2 + O_2 \]
- For Rubidium Nitrate (RbNO3):
\[ 2RbNO_3 \rightarrow 2RbNO_2 + O_2 \]
- For Cesium Nitrate (CsNO3):
\[ 2CsNO_3 \rightarrow 2CsNO_2 + O_2 \]
- For Francium Nitrate (FrNO3):
\[ 2FrNO_3 \rightarrow 2FrNO_2 + O_2 \]

4. **Identify the Products**:
From the reactions above, we can see that the products formed from heating these alkali metal nitrates are:
- Alkali metal nitrites (MNO2)
- Oxygen gas (O2)

5. **Conclusion**:
The products formed from heating alkali metal nitrates (except LiNO3) are:
- MNO2 (alkali metal nitrite)
- O2 (oxygen gas)

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