how many of the following species are aromatic in nature cyclopentadienyl cation, cyclopentadienyl anion, tropylium cation, azulene, cyclopropenyl cation, tetrahydrofuran, cyclooctatetraene, furan , cycloheptatriene

Explanation

To determine how many of the given species are aromatic in nature, we will evaluate each compound based on the criteria for aromaticity. A compound is considered aromatic if it meets the following criteria:

1. It is cyclic.
2. It is planar (or nearly planar).
3. It follows Huckel's rule, which states that it must have (4n + 2) π electrons, where n is a non-negative integer.

Now, let's analyze each species:

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