In the laboratory, `SO_2` is prepared by

Options

A. dil. H2SO, and sodium sulphide
B. conc. `H_2 SO_4` and sodium sulphide
C. conc. `H_2 SO_4` and copper heated together
D. None of the above

Explanation

To prepare sulfur dioxide (SO₂) in the laboratory, we can follow these steps based on the reaction between concentrated sulfuric acid and copper:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactants needed for this preparation are concentrated sulfuric acid (H₂SO₄) and copper (Cu).

2. **Set Up the Reaction**:
- When concentrated sulfuric acid reacts with copper, the reaction can be represented as:
\[ \text{Cu} + \text{H}_2\text{SO}_4 \rightarrow \text{CuSO}_4 + \text{H}_2\text{O} + \text{SO}_2 \]
- In this reaction, copper (Cu) is oxidized, and sulfuric acid is reduced, leading to the formation of sulfur dioxide (SO₂).

3. **Balance the Reaction**:
- The balanced chemical equation is:
\[ \text{Cu} + 2 \text{H}_2\text{SO}_4 \rightarrow \text{CuSO}_4 + 2 \text{H}_2\text{O} + \text{SO}_2 \]
- Here, we ensure that the number of atoms for each element is equal on both sides of the equation.

4. **Determine the Correct Option**:
- From the options provided:
- A: Dilute sulfuric acid and sodium sulfite
- B: Concentrated sulfuric acid and sodium sulfite
- C: Concentrated sulfuric acid and copper heated together
- D: None of the above
- The correct option is **C**: Concentrated sulfuric acid and copper heated together.