Which gas is evolved by the treatment of magnesium with very dilute solution of `HNO_(3)`

Options

A. `N_(2)`
B. `NO_(2)`
C. `H_(2)`
D. `H_(2)O`

Explanation

To determine which gas is evolved when magnesium reacts with a very dilute solution of nitric acid (HNO₃), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactants in this case are magnesium (Mg) and very dilute nitric acid (HNO₃).

2. **Understand the Reaction**:
- When magnesium reacts with nitric acid, it typically forms magnesium nitrate (Mg(NO₃)₂) and a gas.

3. **Write the Chemical Equation**:
- The balanced chemical equation for the reaction of magnesium with dilute nitric acid is:
\[ Mg + 2HNO_3 \rightarrow Mg(NO_3)_2 + H_2 \]
- However, in the case of very dilute nitric acid, the reaction does not proceed to produce hydrogen gas (H₂) as it would with other acids.

4. **Identify the Gas Produced**:
- In the presence of very dilute nitric acid, magnesium does not produce hydrogen gas due to the weak oxidizing nature of dilute nitric acid. Instead, it produces nitrogen monoxide (NO) or nitrous oxide (N₂O) depending on the concentration and conditions, but primarily, it leads to the evolution of hydrogen gas (H₂) in this context.

5. **Conclusion**:
- Therefore, the gas evolved when magnesium reacts with very dilute nitric acid is hydrogen gas (H₂).

### Final Answer:
The gas evolved by the treatment of magnesium with very dilute solution of HNO₃ is hydrogen gas (H₂).

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