Question 1

Which of the following substituents on a benzene ring is most likely to activate the ring and direct incoming electrophiles to the ortho and para positions?

Accepted Answer

NH$$_2$$

Question 2

A student treats toluene (methylbenzene) with hot, acidic KMnO$$_4. $$What is the major product?

Accepted Answer

Benzoic acid

Question 3

Which statement best explains why the NO$$_2$$ group is a meta director in electrophilic aromatic substitution?

Accepted Answer

It destabilizes the carbocation intermediate at ortho and para positions due to electron withdrawal by resonance.

Question 4

Which of the following is NOT a source of polycyclic aromatic hydrocarbons (PAHs) in the environment?

Accepted Answer

Photosynthesis in plants

Question 5

Why do halogens act as ortho- and para-directing deactivators in aromatic substitution?

Accepted Answer

Their electron-withdrawing inductive effect outweighs their electron-donating resonance effect.

Question 6

Which of the following alkyl benzenes will NOT be oxidized to a carboxylic acid under strong oxidizing conditions?

Accepted Answer

Isopropylbenzene

Question 7

What is the main health risk associated with exposure to polycyclic aromatic hydrocarbons (PAHs)?

Accepted Answer

DNA damage leading to cancer

Question 8

Which rule applies when two substituents on a benzene ring direct incoming groups to the same position?

Accepted Answer

The new substituent is located at the position directed by both groups.

Question 9

Which of the following best describes the effect of an alkyl group on a benzene ring?

Accepted Answer

Electron-donating by inductive effect

Question 10

A benzene ring has both a methyl group (activator, ortho/para director) and a nitro group (deactivator, meta director) as substituents. Where will a third substituent most likely be added?

Accepted Answer

At the position directed by the methyl group

Question 11

Which of the following substituents is a deactivator and meta director?

Accepted Answer

COOH

Question 12

What is the effect of a substituent that withdraws electron density from the benzene ring by resonance?

Accepted Answer

It deactivates the ring and directs substitution to meta positions.

Question 13

Which of the following is a correct statement about the oxidation of alkyl benzenes?

Accepted Answer

Any alkyl group with a benzylic C-H bond can be oxidized to a carboxylic acid.

Question 14

Which of the following best explains why PAHs are carcinogenic?

Accepted Answer

They intercalate between DNA base pairs and can cause mutations or break the DNA backbone.

Question 15

Which of the following is a correct statement about the resonance effect of halogens on benzene?

Accepted Answer

Halogens donate electrons by resonance, stabilizing the carbocation at ortho and para positions.

Question 16

Which of the following is a real-world example of exposure to PAHs?

Accepted Answer

Eating charred meat from a barbecue

Question 17

Which of the following statements about disubstituted benzene is correct?

Accepted Answer

If two groups direct to different positions, the more powerful activator determines the position.

Question 18

Which of the following is the correct product when p-xylene is oxidized with hot KMnO$$_4$$?

Accepted Answer

Phthalic acid

Question 19

Which of the following substituents is both an ortho/para director and a deactivator?

Accepted Answer

Halogen (e.g., Cl)

Question 20

Which of the following best describes the interplay of inductive and resonance effects in substituted benzenes?

Accepted Answer

Resonance effects can either donate or withdraw electron density, depending on the substituent.

Aromatic Hydrocarbons II: Substituent Effects, Oxidation, and Polycyclic Aromatic Hydrocarbons

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