Question 1

Which of the following best explains why [14]-annulene is aromatic?
Correct answer: It has a continuous conjugated π system and satisfies Hückel's rule.

Accepted Answer

It has a continuous conjugated π system and satisfies Hückel's rule.

Question 2

Dehydro[14]annulene differs from [14]-annulene in its reactivity because:
Correct answer: The triple bond's electrons remain localized, allowing for reactions like nitration.

Accepted Answer

The triple bond's electrons remain localized, allowing for reactions like nitration.

Question 3

Which statement about the nitrogen atom in pyridine is correct?
Correct answer: One electron from nitrogen is in the π system; the lone pair is in an sp2 orbital in the plane of the ring.

Accepted Answer

One electron from nitrogen is in the π system; the lone pair is in an sp2 orbital in the plane of the ring.

Question 4

A molecule is found to be planar, cyclic, and has 10 π electrons. According to Hückel's rule, is it aromatic?
Correct answer: Yes, because 10 = 4n + 2 when n = 2.

Accepted Answer

Yes, because 10 = 4n + 2 when n = 2.

Question 5

Which of the following is NOT a requirement for aromaticity?
Correct answer: The molecule must contain at least one triple bond.

Accepted Answer

The molecule must contain at least one triple bond.

Question 6

A chemist attempts to nitrate dehydro[14]annulene. Which property of this molecule makes this reaction possible?
Correct answer: The triple bond's electrons are localized and not part of the aromatic π system.

Accepted Answer

The triple bond's electrons are localized and not part of the aromatic π system.

Question 7

Which of the following molecules would NOT be aromatic?
Correct answer: A planar, cyclic molecule with 8 π electrons.

Accepted Answer

A planar, cyclic molecule with 8 π electrons.

Question 8

In pyridine, the lone pair of electrons on nitrogen:
Correct answer: Is in an sp2 orbital in the plane of the ring and does not participate in aromaticity.

Accepted Answer

Is in an sp2 orbital in the plane of the ring and does not participate in aromaticity.

Question 9

Which of the following best describes the π electron count for aromaticity according to Hückel's rule?
Correct answer: 4n + 2 π electrons, where n is an integer.

Accepted Answer

4n + 2 π electrons, where n is an integer.

Question 10

A new cyclic compound is discovered. It is planar, has a continuous conjugated π system, and contains 12 π electrons. Is it aromatic?
Correct answer: No, because 12 π electrons do not satisfy Hückel's rule.

Accepted Answer

No, because 12 π electrons do not satisfy Hückel's rule.

Question 11

Which scenario would most likely disrupt the aromaticity of [14]-annulene?
Correct answer: Introducing a non-planar distortion to the ring.

Accepted Answer

Introducing a non-planar distortion to the ring.

Question 12

A student claims that the triple bond in dehydro[14]annulene increases the aromaticity of the molecule. Evaluate this claim.
Correct answer: Incorrect, because the triple bond's electrons are localized and do not participate in aromaticity.

Accepted Answer

Incorrect, because the triple bond's electrons are localized and do not participate in aromaticity.

Question 13

Which of the following best explains why pyridine is aromatic?
Correct answer: The nitrogen atom is sp2 hybridized, and only one of its electrons participates in the π system.

Accepted Answer

The nitrogen atom is sp2 hybridized, and only one of its electrons participates in the π system.

Question 14

Which of the following is a real-world application of understanding aromaticity in molecules like pyridine?
Correct answer: Developing pharmaceuticals that exploit the stability of aromatic heterocycles.

Accepted Answer

Developing pharmaceuticals that exploit the stability of aromatic heterocycles.

Question 15

A molecule is cyclic, planar, and has a continuous conjugated π system. It contains 8 π electrons. What is the best description of its aromaticity?
Correct answer: It is antiaromatic because 8 π electrons do not satisfy Hückel's rule.

Accepted Answer

It is antiaromatic because 8 π electrons do not satisfy Hückel's rule.

Question 16

Which of the following would most likely increase the reactivity of dehydro[14]annulene compared to [14]-annulene?
Correct answer: The presence of a triple bond with localized electrons.

Accepted Answer

The presence of a triple bond with localized electrons.

Aromaticity in [14]-Annulene, Dehydro[14]Annulene, and Pyridine

Study Guide - Practice Questions

Study Guide - Flashcards