(a) (Acenaphthene)

JEE Main 2021 (Online) 1st September Evening Shift Chemistry - Basics of Organic Chemistry Question 146 English Explanation 1

$$\to$$ 10 $$\pi$$e^$$-$$ in cyclic conjugation

$$\Rightarrow$$ Aromatic

"Note: For a compound with multiple cyclic rings to exhibit aromaticity, it must conform to Hückel's rule, which stipulates that the molecule should have (4n+2) π-electrons in the largest periphery of continuous conjugation. Rings with sp³ hybridized carbon atoms are not considered in this context. Despite their potential π-bonds, these rings cannot participate in resonance with π-bonds of the other rings due to the sp³ hybridization, and thus do not contribute to the overall aromaticity of the compound."

(b) JEE Main 2021 (Online) 1st September Evening Shift Chemistry - Basics of Organic Chemistry Question 146 English Explanation 2

JEE Main 2021 (Online) 1st September Evening Shift Chemistry - Basics of Organic Chemistry Question 146 English Explanation 2

$$\to$$ 4 $$\pi$$e^$$-$$ in ring conjugation $$\Rightarrow$$ Anti Aromatic

(c) JEE Main 2021 (Online) 1st September Evening Shift Chemistry - Basics of Organic Chemistry Question 146 English Explanation 3

JEE Main 2021 (Online) 1st September Evening Shift Chemistry - Basics of Organic Chemistry Question 146 English Explanation 3

$$\Rightarrow$$ 4 $$\pi$$e^$$-$$ in ring conjugation $$\Rightarrow$$ Antiaromatic

(d) JEE Main 2021 (Online) 1st September Evening Shift Chemistry - Basics of Organic Chemistry Question 146 English Explanation 4

JEE Main 2021 (Online) 1st September Evening Shift Chemistry - Basics of Organic Chemistry Question 146 English Explanation 4

6$$\pi$$e^$$-$$ in ring conjugation $$\Rightarrow$$ Aromatic