`As_(2)S_(3)+HNO_(3)toH_(3)AsO_(4)+H_(2)SO_(4)+NO` the element
which is oxidised in the reaction is / are

Options

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

Answer

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-by-Step Solution:

1. **Identify the Reactants and Products**:
- Reactants: \( \text{As}_2\text{S}_3 \) (arsenic trisulfide) and \( \text{HNO}_3 \) (nitric acid).
- Products: \( \text{H}_3\text{AsO}_4 \) (arsenic acid), \( \text{H}_2\text{SO}_4 \) (sulfuric acid), and \( \text{NO} \) (nitric oxide).

2. **Determine the Oxidation States**:
- For \( \text{As}_2\text{S}_3 \):
- Let the oxidation state of As be \( x \).
- The oxidation state of S is \(-2\).
- The equation becomes \( 2x + 3(-2) = 0 \) → \( 2x - 6 = 0 \) → \( x = +3 \).
- Thus, As in \( \text{As}_2\text{S}_3 \) has an oxidation state of \( +3 \).

- For \( \text{HNO}_3 \):
- The oxidation state of N is \( +5 \) (common oxidation state in nitric acid).

- For \( \text{H}_3\text{AsO}_4 \):
- Let the oxidation state of As be \( y \).
- The oxidation state of O is \(-2\).
- The equation becomes \( 3(+1) + y + 4(-2) = 0 \) → \( 3 + y - 8 = 0 \) → \( y = +5 \).
- Thus, As in \( \text{H}_3\text{AsO}_4 \) has an oxidation state of \( +5 \).

- For \( \text{H}_2\text{SO}_4 \):
- The oxidation state of S is \( +6 \).

- For \( \text{NO} \):
- The oxidation state of N is \( +2 \).

3. **Compare the Oxidation States**:
- Arsenic (As): Changes from \( +3 \) in \( \text{As}_2\text{S}_3 \) to \( +5 \) in \( \text{H}_3\text{AsO}_4 \) (oxidation occurs).
- Sulfur (S): Changes from \( -2 \) in \( \text{As}_2\text{S}_3 \) to \( +6 \) in \( \text{H}_2\text{SO}_4 \) (oxidation occurs).
- Nitrogen (N): Changes from \( +5 \) in \( \text{HNO}_3 \) to \( +2 \) in \( \text{NO} \) (reduction occurs).

4. **Conclusion**:
- The elements that are oxidized in the reaction are Arsenic (As) and Sulfur (S).

### Final Answer:
The elements that are oxidized in the reaction are Arsenic (As) and Sulfur (S).

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