In the following reaction, `H_2 SO_4` acts as
`2 Ag + H_2 SO_4 rarr Ag_2 SO_4 + 2 H_2 O + SO_2`.

Options

A. Reducing agent
B. Oxidising agent
C. Catalytic agent
D. Dehydration agent

Explanation

To determine the role of sulfuric acid (H₂SO₄) in the reaction:

\[ 2 \text{Ag} + \text{H}_2\text{SO}_4 \rightarrow \text{Ag}_2\text{SO}_4 + 2 \text{H}_2\text{O} + \text{SO}_2 \]

we will analyze the oxidation states of the elements involved in the reaction.

### Step 1: Identify the oxidation states of each element in the reactants and products.

1. **Silver (Ag)**: In its elemental form, silver has an oxidation state of 0.
2. **Sulfuric Acid (H₂SO₄)**:
- Hydrogen (H) has an oxidation state of +1.
- Oxygen (O) has an oxidation state of -2.
- To find the oxidation state of sulfur (S), we can use the formula:
\[ \text{Oxidation state of S} + 2(+1) + 4(-2) = 0 \]
\[ \text{Oxidation state of S} + 2 - 8 = 0 \implies \text{Oxidation state of S} = +6 \]

3. **Products**:
- In \(\text{Ag}_2\text{SO}_4\):
- Silver (Ag) has an oxidation state of +1 (since there are two Ag atoms contributing to a +2 charge, balanced by the sulfate ion).
- Sulfur (S) remains +6 (as in H₂SO₄).
- Oxygen (O) is -2.
- In \(\text{H}_2\text{O}\):
- Hydrogen is +1 and Oxygen is -2.
- In \(\text{SO}_2\):
- Sulfur (S) has an oxidation state of +4 (since the total charge from two -2 oxygen atoms is -4, balancing with +4 from sulfur).

### Step 2: Determine changes in oxidation states.

- **Silver (Ag)**: Changes from 0 (in elemental state) to +1 (in \(\text{Ag}_2\text{SO}_4\)).
- **Sulfur (S)**: Changes from +6 (in H₂SO₄) to +4 (in \(\text{SO}_2\)).

### Step 3: Identify the type of reaction.

- **Oxidation**: The increase in oxidation state of silver from 0 to +1 indicates that silver is oxidized.
- **Reduction**: The decrease in oxidation state of sulfur from +6 to +4 indicates that sulfur is reduced.

### Step 4: Conclusion on the role of H₂SO₄.

Since H₂SO₄ facilitates the oxidation of silver while itself being reduced, it acts as an **oxidizing agent**. An oxidizing agent is a substance that gains electrons (is reduced) while causing another substance to lose electrons (is oxidized).

### Final Answer:
H₂SO₄ acts as an **oxidizing agent** in the reaction.

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