How many re-electrons must a ring system possess in order to exhibit aromatic behaviour ?

Explanation

To determine how many π (pi) electrons a ring system must possess to exhibit aromatic behavior, we can follow these steps:

### Step 1: Understand the Criteria for Aromaticity
A compound must meet certain criteria to be classified as aromatic:
1. It must be cyclic (form a ring).
2. It must be planar (all atoms in the ring must lie in the same plane).
3. Each atom in the ring must be sp² hybridized.
4. It must follow Huckel's rule.
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