In electrolysis of dil. `H_(2) SO_(4)` using platinum electrodes:

Options

A. `H_(2)` is evolved at cathode
B. `SO_(2)` is produced at anode
C. `O_(2)` is obtained at cathode
D. `SO_(2)` is produced at cathode

Answer

To solve the question regarding the electrolysis of dilute sulfuric acid (H₂SO₄) using platinum electrodes, we will analyze the reactions occurring at both the anode and cathode.

### Step-by-step Solution:

1. **Understanding the Electrolysis Process**:
- Electrolysis involves breaking down a compound into its components using electricity. In this case, we are using dilute H₂SO₄, which dissociates into ions in solution:
\[ H_2SO_4 \rightarrow 2H^+ + SO_4^{2-} \]

2. **Identifying the Electrodes**:
- Platinum electrodes are inert and do not participate in the reaction but serve as sites for oxidation and reduction.

3. **Reactions at the Anode**:
- At the anode, oxidation occurs (loss of electrons). The sulfate ions (SO₄²⁻) can undergo oxidation:
\[ SO_4^{2-} \rightarrow SO_2 + 2O^{2-} + 4e^- \]
- The oxygen ions (O²⁻) can react with water to produce more electrons and water:
\[ 4OH^- \rightarrow 2H_2O + 4e^- \quad \text{(from water)} \]
- The standard electrode potential for this oxidation reaction is approximately 1.23 V.

4. **Reactions at the Cathode**:
- At the cathode, reduction occurs (gain of electrons). The hydrogen ions (H⁺) from the dissociation of sulfuric acid can gain electrons to form hydrogen gas:
\[ 2H^+ + 2e^- \rightarrow H_2 \]
- The standard electrode potential for this reduction reaction is 0.00 V.

5. **Determining Which Reaction Occurs**:
- The reaction that occurs at the anode is favored if its electrode potential is lower than that at the cathode. Since 1.23 V (anode) is greater than 0.00 V (cathode), the oxidation of sulfate ions will occur at the anode, while hydrogen gas will be produced at the cathode.

6. **Final Products**:
- Therefore, during the electrolysis of dilute H₂SO₄:
- At the anode: Sulfur dioxide (SO₂) is produced.
- At the cathode: Hydrogen gas (H₂) is liberated.

### Conclusion:
- The correct answer is that hydrogen gas evolves at the cathode and sulfur dioxide is produced at the anode.