Which of the following compounds is considered aromatic according to Hückel's rule?

• A. $C_5{H}_{10}$ (cyclopentane)
• B. $C_4{H}_8$ (cyclobutene)
• C. $C_7{H}_8$ (toluene)
• D. $C_6{H}_6$ (benzene)

Answer: (D)

Verified step by step guidance

1. Recall that Hückel's rule states a compound is aromatic if it is cyclic, planar, fully conjugated, and contains (4n + 2) π electrons, where n is a non-negative integer (0, 1, 2, ...).
2. Analyze each compound to determine if it meets the criteria: it must be cyclic and planar with a continuous overlap of p orbitals (fully conjugated system).
3. Count the number of π electrons in each compound. For example, benzene (C\6H\6) has 6 π electrons from its three double bonds.
4. Check if the number of π electrons fits the formula (4n + 2). For benzene, 6 π electrons correspond to n = 1, which satisfies Hückel's rule.
5. Conclude that among the given compounds, only benzene meets all the criteria of aromaticity according to Hückel's rule.