Exams › JEE Advanced › Chemistry

Two statements are given. Assertion A: [6]Annulene, [8]Annulene and cis-[10]Annulene are aromatic, non-aromatic and aromatic respectively. Reason R: One of the conditions for aromaticity is that the ring be planar. Select the most appropriate response.

1. Both A and R are correct and R is the correct explanation of A.
2. Both A and R are correct but R is NOT the correct explanation of A.
3. A is correct but R is not correct.
4. A is not correct but R is correct.

Correct answer: Both A and R are correct and R is the correct explanation of A.

Solution

[6]Annulene = benzene: planar, 6 pi e (4n+2, n=1), aromatic. [8]Annulene = cyclooctatetraene: 8 pi e (4n) and non-planar tub shape, so non-aromatic. cis-[10]Annulene: 10 pi e (4n+2, n=2) and the cis isomer can be planar, so aromatic. Thus A is correct. Planarity is indeed a requirement and it is exactly the property explaining why [8]annulene fails while the others succeed, so R correctly explains A.

Related JEE Advanced Chemistry questions

• Even though the chlorination of methane releases energy, why is a high temperature necessary for the reaction to occur?
• Acetylene (HC≡CH) undergoes the following two-step transformation: Step 1: Passed over a red-hot iron tube at 873 K (cyclic trimerisation). Step 2: The product of Step 1 is treated with CO, HCl, and AlCl3 (Gattermann-Koch reaction). How many carbon atoms in the final product are sp2 hybridised?
• Which of the following species is non-aromatic (i.e., neither aromatic nor antiaromatic)?
• Among the following compounds, which one produces ONLY oxalic acid (HOOC-COOH) as the major product when treated with O3 followed by H2O2?
• Which of the following reactions proceeds in the forward direction as written?
• What reagent(s) can convert 1,3-dibromopropane (Br-CH2-CH2-CH2-Br) into acetylene (H-C≡C-H)?

⚔️ Practice JEE Advanced Chemistry free + battle 1v1 →