Assertion : Pure `N_(2)` is obtained from `Ba(N_(3))_(2)` but not from `(NH_(4))_(2)Cr_(2)O_(7)`
Reason : On decomposition `(NH_(4))_(2)Cr_(2)O_(7)` gives `O_(2)` gas.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Analyze the Assertion
The assertion states that pure \(N_2\) is obtained from \(Ba(N_3)_2\) but not from \((NH_4)_2Cr_2O_7\).

- **Decomposition of \(Ba(N_3)_2\)**:
When barium azide (\(Ba(N_3)_2\)) decomposes, it produces barium metal and nitrogen gas. The reaction can be represented as:
\[ Ba(N_3)_2 \rightarrow Ba + 3N_2 \]
Here, the nitrogen gas (\(N_2\)) produced is in its pure form because it is generated as a product without any other gases or compounds being formed in the reaction.

### Step 2: Analyze the Reason
The reason states that on decomposition, \((NH_4)_2Cr_2O_7\) gives \(O_2\) gas.

- **Decomposition of \((NH_4)_2Cr_2O_7\)**:
The decomposition of ammonium dichromate (\((NH_4)_2Cr_2O_7\)) upon heating does not produce oxygen gas. Instead, it produces nitrogen gas, chromium(III) oxide, and water. The reaction can be represented as:
\[ (NH_4)_2Cr_2O_7 \rightarrow N_2 + Cr_2O_3 + 4H_2O \]
Thus, the reason provided is incorrect as it does not produce \(O_2\) gas.

### Conclusion
Based on the analysis:
- The assertion is **true** because pure \(N_2\) is indeed obtained from \(Ba(N_3)_2\).
- The reason is **false** because \((NH_4)_2Cr_2O_7\) does not produce \(O_2\) on decomposition.

### Final Answer
The assertion is true, but the reason is false.

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