Question 1

Which of the following molecules is aromatic according to Hückel's rule?

Accepted Answer

$$C_6H_6 ($$benzene)

Question 2

A 1,3-butadiene molecule is an example of which of the following?

Accepted Answer

A conjugated diene

Question 3

Which of the following best explains why benzene is unusually stable?

Accepted Answer

It has a delocalized $$\pi$$ electron system over a planar ring

Question 4

Which of the following is the correct product distribution for the reaction of 1,3-butadiene with HBr at low temperature ($$-80^\circC$$)?

Accepted Answer

80% 1,2-addition product, 20% 1,4-addition product

Question 5

Which of the following statements about electrophilic aromatic substitution is TRUE?

Accepted Answer

The intermediate is a carbocation that is nonaromatic

Question 6

Which of the following substituents is an electron-withdrawing group by resonance?

Accepted Answer

$$-NO_2$

Question 7

A molecule is considered conjugated if:

Accepted Answer

It has alternating single and double bonds with adjacent $$p$$ orbitals

Question 8

Which of the following best describes the hybridization of carbon atoms in benzene?

Accepted Answer

All carbons are $$sp^2$$ hybridized

Question 9

Which of the following is NOT a criterion for aromaticity?

Accepted Answer

The molecule must contain at least one heteroatom

Question 10

Which of the following statements about UV-Vis absorption in conjugated dienes is correct?

Accepted Answer

Increasing conjugation shifts $$\lambda_{max} to $$longer wavelengths

Question 11

Which of the following best describes the effect of an $$-OH$$ group on a benzene ring?

Accepted Answer

It is an electron-donating group by resonance

Question 12

Which of the following is the correct name for a benzene ring with a $$-CH_2CH_3$$ group attached?

Accepted Answer

Ethylbenzene

Question 13

Which of the following is true about the intermediate formed during electrophilic aromatic substitution?

Accepted Answer

It is stabilized by resonance

Question 14

Which of the following best explains why [10]-annulene is not aromatic?

Accepted Answer

It is not planar due to steric strain

Question 15

Which of the following is a correct statement about the effect of temperature on the addition of HBr to 1,3-butadiene?

Accepted Answer

At high temperature, the 1,4-addition product is favored

Question 16

Which of the following groups is a meta-directing deactivator in electrophilic aromatic substitution?

Accepted Answer

$$-NO_2$

Question 17

Which of the following best describes the hybridization and orbital overlap in a conjugated diene?

Accepted Answer

Each carbon is $$sp^2$$ hybridized with overlapping $$p$$ orbitals

Question 18

Which of the following statements about antiaromatic compounds is correct?

Accepted Answer

They have $$4n$$ $$\pi$$ electrons and are destabilized by electron delocalization

Question 19

Which of the following is the correct effect of an $$-NH_2$ group on a benzene ring?

Accepted Answer

It is an electron-donating group by resonance

Question 20

Which of the following best describes the effect of conjugation on the energy gap between ground and excited states in a molecule?

Accepted Answer

Conjugation decreases the energy gap

Conjugation, Resonance, Dienes, and Aromatic Compounds: Study Notes

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