Hot and conc. Nitric acid when reacts with copper, the gas obtained is

Options

A. `N_(2)`
B. Nitrous oxide
C. `NO`
D. `NO_(2)`

Explanation

To determine the gas produced when hot and concentrated nitric acid reacts with copper, we can follow these steps:

### Step 1: Identify the Reactants
The reactants in this reaction are copper (Cu) and concentrated nitric acid (HNO3).

### Step 2: Write the Reaction Equation
When copper reacts with hot and concentrated nitric acid, the following reaction occurs:
\[ \text{Cu} + 4 \text{HNO}_3 \rightarrow \text{Cu(NO}_3\text{)}_2 + 2 \text{NO}_2 + 2 \text{H}_2\text{O} \]
In this reaction, copper nitrate (Cu(NO3)2), nitrogen dioxide (NO2), and water (H2O) are formed.

### Step 3: Identify the Gas Produced
From the balanced chemical equation, we can see that nitrogen dioxide (NO2) is one of the products of the reaction.

### Step 4: Conclusion
Thus, the gas obtained when hot and concentrated nitric acid reacts with copper is nitrogen dioxide (NO2).

### Final Answer
The gas obtained is **NO2** (option 4).

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