When zinc reacts with very dilute `HNO_(3)`, the oxidation state of nitrogen changes from:

Options

A. `+5` to +1
B. `+5` to -3
C. `+5` to +4
D. `+5` to +3

Answer

To determine the change in oxidation state of nitrogen when zinc reacts with very dilute HNO₃, we can follow these steps:

### Step 1: Write the Reaction
When zinc reacts with very dilute nitric acid (HNO₃), the products formed are ammonium nitrate (NH₄NO₃) and zinc nitrate (Zn(NO₃)₂). The balanced chemical equation can be written as:

\[ 4 \text{Zn} + 10 \text{HNO}_3 \rightarrow 4 \text{Zn(NO}_3\text{)}_2 + \text{NH}_4\text{NO}_3 + 3 \text{H}_2\text{O} \]

### Step 2: Identify the Oxidation States
Next, we need to identify the oxidation states of nitrogen in the reactants and products.

1. **In HNO₃**:
- The oxidation state of nitrogen (N) can be calculated as follows:
\[ X + 1 + 3(-2) = 0 \quad \text{(since the overall charge is neutral)} \]
\[ X - 5 = 0 \implies X = +5 \]
Thus, the oxidation state of nitrogen in HNO₃ is +5.

2. **In NH₄NO₃**:
- The ammonium ion (NH₄⁺) has nitrogen with an oxidation state calculated as:
\[ X + 4(1) = +1 \quad \text{(since the overall charge is +1)} \]
\[ X + 4 = 1 \implies X = -3 \]
- In the nitrate ion (NO₃⁻), the oxidation state of nitrogen is:
\[ Y + 3(-2) = -1 \quad \text{(since the overall charge is -1)} \]
\[ Y - 6 = -1 \implies Y = +5 \]
Thus, in NH₄NO₃, nitrogen has an oxidation state of -3 in the ammonium ion and +5 in the nitrate ion.

### Step 3: Determine the Change in Oxidation State
From the above calculations:
- The oxidation state of nitrogen changes from +5 (in HNO₃) to -3 (in NH₄⁺).
- The oxidation state of nitrogen in the nitrate ion remains +5.

### Conclusion
Thus, the change in oxidation state of nitrogen when zinc reacts with very dilute HNO₃ is from +5 to -3.

### Final Answer
The oxidation state of nitrogen changes from +5 to -3.

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