Pure nitrogen is prepared in the laboratory by heating a mixture of

Options

A. `NH_(4)OH+NaCl`
B. `NH_(4)NO_(3)+NaCl`
C. `NH_(4)Cl+NaOH`
D. `NH_(4)Cl+NaNO_(2)`

Explanation

To prepare pure nitrogen gas (N₂) in the laboratory, we can follow these steps:

### Step 1: Identify the Reactants
We need to identify the correct mixture of compounds that will yield nitrogen gas upon heating. The options given are:
1. NH₄OH
2. NaCl
3. NH₄NO₃
4. NH₄Cl and NaOH
5. NH₄Cl and NaNO₂

### Step 2: Analyze the Reactions
Among the options, we focus on the combination of ammonium chloride (NH₄Cl) and sodium nitrate (NaNO₂).

### Step 3: Write the Reaction
When ammonium chloride (NH₄Cl) reacts with sodium nitrate (NaNO₂) upon heating, the reaction can be represented as follows:

\[ \text{NH}_4\text{Cl} + \text{NaNO}_2 \rightarrow \text{N}_2 + \text{NaCl} + \text{H}_2\text{O} \]

### Step 4: Identify the Products
From the reaction, the products formed are:
- Nitrogen gas (N₂)
- Sodium chloride (NaCl)
- Water (H₂O)

### Step 5: Conclusion
Thus, the correct answer is that pure nitrogen is prepared in the laboratory by heating a mixture of ammonium chloride (NH₄Cl) and sodium nitrate (NaNO₂). Therefore, the answer is option D.

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