When a solution of nitrite acidified with dilute hydrochloric acid is treated with solid urea, the nitrile is decomposed, and nitrogen and carbon dioxide are evolved.

Explanation

To solve the question regarding the reaction of nitrite acidified with dilute hydrochloric acid treated with solid urea, we will follow these steps:

### Step 1: Identify the Reactants
The reactants in this reaction are:
- Nitrite ion (NO2^-)
- Dilute hydrochloric acid (HCl)
- Solid urea (CO(NH2)2)

### Step 2: Acidification of Nitrite
When the nitrite ion (NO2^-) is treated with dilute hydrochloric acid (HCl), it forms nitrous acid (HNO2):
\[ \text{NO}_2^- + \text{HCl} \rightarrow \text{HNO}_2 + \text{Cl}^- \]

### Step 3: Reaction of Nitrous Acid with Urea
Next, the nitrous acid (HNO2) reacts with solid urea (CO(NH2)2). The reaction can be represented as:
\[ \text{HNO}_2 + \text{CO(NH}_2)_2 \rightarrow \text{N}_2 + \text{CO}_2 + \text{H}_2\text{O} \]

### Step 4: Balancing the Reaction
To balance the reaction, we need to ensure that the number of atoms of each element is the same on both sides. The balanced equation is:
\[ 2 \text{HNO}_2 + \text{CO(NH}_2)_2 \rightarrow 2 \text{N}_2 + \text{CO}_2 + 3 \text{H}_2\text{O} \]

### Step 5: Identify the Products
From the balanced reaction, we can see that the products formed are:
- Nitrogen gas (N2)
- Carbon dioxide (CO2)
- Water (H2O)

### Final Summary
In summary, when a solution of nitrite acidified with dilute hydrochloric acid is treated with solid urea, nitrogen gas and carbon dioxide are evolved along with water.

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