Question 1

Which of the following statements best explains why benzene is more stable than expected based on the heat of hydrogenation of cyclohexene?

Accepted Answer

Benzene's stability is due to resonance delocalization of its $	ext{6} 	ext{pi}$ electrons over the entire ring, resulting in aromatic stabilization.

Question 2

Which of the following compounds is NOT aromatic?

Accepted Answer

Cyclobutadiene

Question 3

Which of the following is the correct order of acidity for the following compounds: phenol, ethanol, and cyclohexanol?

Accepted Answer

Phenol > ethanol > cyclohexanol

Question 4

Which of the following statements about the nitration of benzene is TRUE?

Accepted Answer

The nitronium ion ($NO_2^+$) acts as the electrophile in the reaction.

Question 5

Which of the following substituents is a meta-director in electrophilic aromatic substitution reactions?

Accepted Answer

$-NO_2$

Question 6

A student attempts to brominate anisole ($C_6H_5OCH_3$) using $Br_2$ and $FeBr_3$. Which position on the aromatic ring will be most favored for substitution?

Accepted Answer

Ortho and para to the methoxy group

Question 7

Which of the following best describes the product of Friedel-Crafts alkylation of benzene with 2-chloropropane and $AlCl_3$?

Accepted Answer

Isopropylbenzene (cumene)

Question 8

Which of the following is a limitation of the Friedel-Crafts alkylation reaction?

Accepted Answer

Carbocation rearrangements can lead to unexpected products.

Question 9

Which of the following statements about the resonance structures of the cyclohexadienyl cation (arenium ion) formed during electrophilic aromatic substitution is correct?

Accepted Answer

The positive charge is delocalized over three carbons of the ring.

Question 10

Which of the following best explains why aniline ($C_6H_5NH_2$) is a stronger base than nitrobenzene ($C_6H_5NO_2$)?

Accepted Answer

The amino group donates electron density to the ring, increasing basicity.

Question 11

Which of the following is the correct product for the sulfonation of benzene using fuming sulfuric acid?

Accepted Answer

Benzenesulfonic acid ($C_6H_5SO_3H$)

Question 12

Which of the following statements about the reactivity of benzene compared to alkenes in electrophilic addition reactions is correct?

Accepted Answer

Benzene is less reactive than alkenes in electrophilic addition reactions due to aromatic stabilization.

Question 13

Which of the following is the best explanation for why $p$-nitroaniline is less basic than aniline?

Accepted Answer

The nitro group at the para position withdraws electron density from the amino group via resonance and induction.

Question 14

Which of the following is a correct statement about the effect of substituents on the rate of electrophilic aromatic substitution?

Accepted Answer

Electron-donating groups increase the rate by stabilizing the intermediate carbocation.

Question 15

Which of the following is the correct order of reactivity toward electrophilic aromatic substitution for the following compounds: toluene, benzene, nitrobenzene?

Accepted Answer

Toluene > benzene > nitrobenzene

Question 16

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

Accepted Answer

sp$^2$ hybridized, planar

Question 17

Which of the following is a correct statement about the Diels-Alder reaction?

Accepted Answer

It is a [4+2] cycloaddition reaction between a diene and a dienophile.

Question 18

Which of the following is the major product when 1,3-butadiene reacts with ethene in a Diels-Alder reaction?

Accepted Answer

Cyclohexene

Question 19

Which of the following best explains why cyclopentadiene is not aromatic?

Accepted Answer

It does not have a continuous ring of p orbitals.

Question 20

Which of the following is the correct product when benzene is treated with $CH_3Cl$ and $AlCl_3$?

Accepted Answer

Toluene

Aromaticity, Benzene, and Aromatic Compounds: Key Concepts and Reactions

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