Among the nitrate of alkali metals which one can be decomposed to its oxide on strong heating?

Options

A. `LiNO_(3)`
B. `NaNO_(3)`
C. `KNO_(3)`
D. `RbNO_(3)`

Answer

To determine which nitrate of alkali metals can be decomposed to its oxide upon strong heating, we will analyze the decomposition reactions of the nitrates of alkali metals one by one.

### Step-by-Step Solution:

1. **Identify the Nitrates of Alkali Metals**: The alkali metals include Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), and Cesium (Cs). Their nitrates are LiNO3, NaNO3, KNO3, RbNO3, and CsNO3.

2. **Decomposition of Sodium Nitrate (NaNO3)**:
- When NaNO3 is heated, it decomposes according to the reaction:
\[ 2 \text{NaNO}_3 \rightarrow 2 \text{NaNO}_2 + \text{O}_2 \]
- This reaction produces sodium nitrite (NaNO2) and oxygen gas (O2), but no sodium oxide (Na2O). Thus, NaNO3 does not yield an oxide.

3. **Decomposition of Potassium Nitrate (KNO3)**:
- Upon heating KNO3, the reaction is:
\[ 2 \text{KNO}_3 \rightarrow 2 \text{KNO}_2 + \text{O}_2 \]
- Similar to NaNO3, this produces potassium nitrite (KNO2) and oxygen gas (O2), but no potassium oxide (K2O). Therefore, KNO3 also does not yield an oxide.

4. **Decomposition of Rubidium Nitrate (RbNO3)**:
- When RbNO3 is heated, it decomposes as follows:
\[ 2 \text{RbNO}_3 \rightarrow 2 \text{RbNO}_2 + \text{O}_2 \]
- This reaction produces rubidium nitrite (RbNO2) and oxygen gas (O2), but no rubidium oxide (Rb2O). Hence, RbNO3 does not yield an oxide.

5. **Decomposition of Lithium Nitrate (LiNO3)**:
- When LiNO3 is heated, it decomposes according to the reaction:
\[ 2 \text{LiNO}_3 \rightarrow \text{Li}_2\text{O} + 2 \text{NO}_2 + \text{O}_2 \]
- This reaction produces lithium oxide (Li2O), nitrogen dioxide (NO2), and oxygen gas (O2). Therefore, LiNO3 does yield an oxide.

6. **Conclusion**: Among the nitrates of alkali metals, only lithium nitrate (LiNO3) can be decomposed to its oxide (Li2O) upon strong heating.

### Final Answer:
The nitrate of alkali metal that can be decomposed to its oxide on strong heating is **LiNO3** (Lithium Nitrate).

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