`A + NaNO_2 to N_2O + NaCl + 2H_2O` in this reaction A can be

Options

A. `H_2SO_4`.dil
B. `H_3PO_4`
C. `NH_2OH.HCl`
D. `dil.HCl`

Answer

To determine the compound A in the reaction with sodium nitrite (NaNO₂) that produces nitrous oxide (N₂O), sodium chloride (NaCl), and water (H₂O), we can follow these steps:

### Step 1: Analyze the Reaction
The reaction provided is:
\[ A + NaNO_2 \rightarrow N_2O + NaCl + 2H_2O \]

Here, we need to identify what compound A could be that reacts with sodium nitrite to yield the products mentioned.

### Step 2: Identify the Products
From the products, we see:
- N₂O (nitrous oxide) contains two nitrogen atoms.
- NaCl indicates the presence of a chloride ion.
- 2H₂O indicates the formation of water.

### Step 3: Determine the Nitrogen Source
Since N₂O has two nitrogen atoms, A must contain at least one nitrogen atom to balance the nitrogen atoms in the products.

### Step 4: Consider Possible Candidates for A
Given the presence of NaCl, A should likely be a nitrogen-containing compound that can release chloride ions during the reaction. Common candidates that can react with NaNO₂ include:
- Hydroxylamine (NH₂OH)
- Ammonium salts
- Other nitrogen compounds

### Step 5: Evaluate Hydroxylamine
Hydroxylamine (NH₂OH) is a nitrogen compound that can react with NaNO₂. When hydroxylamine is treated with NaNO₂ in the presence of an acid (like HCl), it can lead to the formation of N₂O.

### Step 6: Write the Complete Reaction
The complete reaction can be written as:
\[ NH_2OH + NaNO_2 + HCl \rightarrow N_2O + NaCl + 2H_2O \]

### Conclusion
Thus, the compound A can be identified as hydroxylamine (NH₂OH) in the presence of hydrochloric acid (HCl).

### Final Answer
A can be \( NH_2OH \) (hydroxylamine) in the presence of HCl.

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