Chemistry - GOC Question with Solution | TestHub
Answer the following by appropriately matching the lists based on the information given in the paragraph.
List - I | List - II |
|---|---|
(P)
| (1) Aromatic |
(Q)
| (2) Non aromatic |
(R)
| (3) Antiaromatic |
(S)
| (4) Homocyclic |
| (5) Heterocyclic |
| (6) Unstable at room temperature |
Which of the following options has the CORRECT combination considering List-I and List-II ?
Options:
Answer:
Solution:
P is pyrrole, which is aromatic (6π electrons due to participation of N lone pair).
Q is protonated pyrrole, so N lone pair is no longer available; it is non-aromatic and still heterocyclic, not homocyclic.
R is cyclopentadienone. It contains a 4π electron cyclic conjugated system, making it antiaromatic, therefore highly unstable and generally unstable at room temperature.
S is the tropylium ion, which has 6π electrons and is aromatic, not antiaromatic.
Hence only the matching R → Unstable at room temperature (6) is correct.