A : `NaN_(3) and Na_(3)` N both are stable.
R : Na when reacted with atmospheric nitrogen at different temperature forms. Stable `NaN_(3) and Na_(3)N`

Options

A. If both Assertion & Reason are true and the reason is the correct explanantion of the assertion, then mark (1).
B. If both Assertion & Reason are true and the reason is the correct explanantion of the assertion, then mark (2).
C. If Assertion is true statement but Reason is false. Them mark (3).
D. If both Assertion and reason are false statement, then mark (4).

Answer

To solve the question, we need to analyze both the assertion (A) and the reason (R) provided.

**Assertion (A)**: NaN₃ (sodium azide) and Na₃N (sodium nitride) are both stable.

**Reason (R)**: Sodium (Na) when reacted with atmospheric nitrogen at different temperatures forms stable NaN₃ and Na₃N.

### Step-by-Step Solution:

1. **Evaluate the Assertion (A)**:
- Sodium azide (NaN₃) is known to be stable under normal conditions but can decompose when heated above its melting point (275 °C) to release nitrogen gas.
- Sodium nitride (Na₃N), on the other hand, is known to be unstable. It can be formed under specific conditions but is not stable in the same way as sodium azide.

**Conclusion for A**: The assertion is **false** because while NaN₃ is stable, Na₃N is not.

2. **Evaluate the Reason (R)**:
- The reason states that sodium reacts with atmospheric nitrogen to form stable NaN₃ and Na₃N. However, sodium does not readily react with nitrogen in the atmosphere. Instead, sodium is typically stored in kerosene or an inert atmosphere to prevent its reaction with air.
- The formation of NaN₃ can occur under specific conditions, but Na₃N is not considered stable.

**Conclusion for R**: The reason is also **false** because sodium does not react with atmospheric nitrogen to form these compounds.

3. **Final Conclusion**:
- Since both the assertion and the reason are false, the correct answer is option D: Both assertion and reason are false statements.