When dilute nitric acid is added to copper turning, the gas evolved is 

Options

A. `NO`
B. `N_2O`
C. `NO_2`
D. `H_2`

Answer

To determine the gas evolved when dilute nitric acid is added to copper turnings, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactants in this reaction are copper (Cu) and dilute nitric acid (HNO3).

2. **Write the Chemical Reaction**:
- When copper reacts with dilute nitric acid, the products formed are copper(II) nitrate (Cu(NO3)2), nitrogen dioxide (NO2), and water (H2O).
- The unbalanced reaction can be written as:
\[ \text{Cu} + \text{HNO}_3 \rightarrow \text{Cu(NO}_3\text{)}_2 + \text{NO}_2 + \text{H}_2\text{O} \]

3. **Balance the Chemical Equation**:
- To balance the equation, we need to ensure that the number of atoms for each element is the same on both sides. The balanced equation is:
\[ 4 \text{HNO}_3 + \text{Cu} \rightarrow 2 \text{NO}_2 + 2 \text{H}_2\text{O} + \text{Cu(NO}_3\text{)}_2 \]

4. **Identify the Gas Evolved**:
- From the balanced equation, we can see that nitrogen dioxide (NO2) is one of the products formed in the reaction.
- Therefore, when dilute nitric acid is added to copper turnings, the gas evolved is nitrogen dioxide (NO2).

5. **Conclusion**:
- The gas evolved when dilute nitric acid is added to copper turnings is NO2.

### Final Answer:
The gas evolved is nitrogen dioxide (NO2).

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