What happens when aluminium is treated with conc. `HNO_(3)`?

Explanation

### Step-by-Step Solution:

1. **Understanding the Reactants**:
- We are dealing with aluminum (Al) and concentrated nitric acid (HNO3). Aluminum is a reactive metal, while nitric acid is a strong oxidizing agent.

2. **Initial Reaction**:
- When aluminum is treated with concentrated nitric acid, it initially reacts. However, aluminum is known to form a protective oxide layer (Al2O3) when exposed to air.

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