See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Anti-aromaticity: π-electron Requirement **Hückel's Rule for Aromaticity:** A cyclic, planar, fully conjugated compound is aromatic when it has $(4n + 2)$ π-electrons (where $n = 0, 1, 2, 3...$) **Anti-aromaticity Definition:** Anti-aromatic compounds are cyclic, planar, fully conjugated systems that are **destabilized** due to electron configuration. They follow the opposite pattern. **Anti-aromatic π-electron count:** Anti-aromatic compounds have $4n$ π-electrons: - $n = 0$: 0 π-electrons - $n = 1$: 4 π-electrons (e.g., cyclobutadiene, $C_4H_4^{2-}$) - $n = 2$: 8 π-electrons (e.g., cyclooctatetraene anion) **Why $4n$ causes anti-aromaticity:** According to molecular orbital theory, $4n$ π-electrons result in **unpaired electrons in the HOMO level**, creating a destabilized, highly reactive state with paramagnetism and ring-strain — characteristic of anti-aromatic compounds. **Answer: (A) $4n$ π-electrons**