In the reaction , `As_(2)S_(3) + HNO_3 rarr H_3AsO_(4) +H_(2)SO_(4) +NO` , the element oxidised is/are :

Options

A. As only
B. S only
C. N only
D. As and S both

Explanation

To determine which element is oxidized in the reaction \( \text{As}_2\text{S}_3 + \text{HNO}_3 \rightarrow \text{H}_3\text{AsO}_4 + \text{H}_2\text{SO}_4 + \text{NO} \), we need to analyze the oxidation states of the elements involved in the reaction.

### Step 1: Assign oxidation states in the reactants
1. **For \( \text{As}_2\text{S}_3 \)**:
- Let the oxidation state of arsenic (As) be \( x \) and that of sulfur (S) be \( y \).
- The equation can be set up as:
\[ 2x + 3y = 0 \]
- Knowing that sulfur typically has an oxidation state of \(-2\):
\[ 2x + 3(-2) = 0 \implies 2x - 6 = 0 \implies 2x = 6 \implies x = +3 \]
- Thus, the oxidation state of arsenic in \( \text{As}_2\text{S}_3 \) is \( +3 \) and sulfur is \( -2 \).

2. **For \( \text{HNO}_3 \)**:
- Let the oxidation state of nitrogen (N) be \( x \).
- The equation can be set up as:
\[ +1 + x + 3(-2) = 0 \implies 1 + x - 6 = 0 \implies x = +5 \]
- Thus, the oxidation state of nitrogen in \( \text{HNO}_3 \) is \( +5 \).

### Step 2: Assign oxidation states in the products
1. **For \( \text{H}_3\text{AsO}_4 \)**:
- Let the oxidation state of arsenic be \( x \).
- The equation can be set up as:
\[ 3(+1) + x + 4(-2) = 0 \implies 3 + x - 8 = 0 \implies x = +5 \]
- Thus, the oxidation state of arsenic in \( \text{H}_3\text{AsO}_4 \) is \( +5 \).

2. **For \( \text{H}_2\text{SO}_4 \)**:
- Let the oxidation state of sulfur be \( y \).
- The equation can be set up as:
\[ 2(+1) + y + 4(-2) = 0 \implies 2 + y - 8 = 0 \implies y = +6 \]
- Thus, the oxidation state of sulfur in \( \text{H}_2\text{SO}_4 \) is \( +6 \).

3. **For \( \text{NO} \)**:
- Let the oxidation state of nitrogen be \( z \).
- The equation can be set up as:
\[ z + (-2) = 0 \implies z = +2 \]
- Thus, the oxidation state of nitrogen in \( \text{NO} \) is \( +2 \).

### Step 3: Determine changes in oxidation states
- **Arsenic**: Changes from \( +3 \) in \( \text{As}_2\text{S}_3 \) to \( +5 \) in \( \text{H}_3\text{AsO}_4 \) (oxidation).
- **Sulfur**: Changes from \( -2 \) in \( \text{As}_2\text{S}_3 \) to \( +6 \) in \( \text{H}_2\text{SO}_4 \) (oxidation).
- **Nitrogen**: Changes from \( +5 \) in \( \text{HNO}_3 \) to \( +2 \) in \( \text{NO} \) (reduction).

### Conclusion
The elements that are oxidized in the reaction are **arsenic and sulfur**.

### Final Answer
The element oxidized is/are: **Arsenic and Sulfur**.

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