Why the wooden shelf under the reagent bottle containing concentrated `H_2SO_4` blackens after some time?

Explanation

To understand why the wooden shelf under the reagent bottle containing concentrated H₂SO₄ blackens over time, we can break down the explanation into several steps:

### Step-by-Step Solution:

1. **Identify the Nature of Concentrated H₂SO₄**:
- Concentrated sulfuric acid (H₂SO₄) is known to be a strong dehydrating agent. This means it has the ability to remove water (H₂O) from other substances.

**Hint**: Remember that dehydrating agents are substances that can absorb moisture or remove water from other materials.
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