When aluminium is heated with conc. `H_(2)SO_(4)`

Options

A. (a) aluminium becomes passive
B. (b) hydrogen is liberated
C. (c) oxygen is liberated
D. (d) sulphur dioxide is liberated

Explanation

**Step-by-Step Solution:**

1. **Understanding the Reaction**: When aluminum (Al) is heated with concentrated sulfuric acid (H₂SO₄), a chemical reaction occurs. Concentrated sulfuric acid acts as an oxidizing agent.

2. **Oxidation of Aluminum**: In this reaction, aluminum is oxidized. The oxidation state of aluminum changes as it reacts with the sulfuric acid.

3. **Formation of Aluminum Sulfate**: The aluminum reacts with the concentrated sulfuric acid to form aluminum sulfate (Al₂(SO₄)₃).

4. **Evolution of Gases**: During this reaction, sulfur dioxide (SO₂) gas is evolved as a byproduct. This is a characteristic of the reaction between aluminum and concentrated sulfuric acid.

5. **Water Production**: Water (H₂O) is also produced in the reaction.

6. **Balancing the Reaction**: The balanced chemical equation for the reaction can be written as:
\[ 2Al + 6H₂SO₄ \rightarrow Al₂(SO₄)₃ + 3SO₂ + 6H₂O \]

7. **Identifying the Products**: From the balanced equation, we can see that the products of the reaction are aluminum sulfate, sulfur dioxide, and water.

8. **Conclusion**: The main characteristic of this reaction is the liberation of sulfur dioxide gas.

**Final Answer**: When aluminum is heated with concentrated H₂SO₄, sulfur dioxide gas is evolved.

---