NEET Chemistry: Electrophilic substitution Practice Questions
14 free multiple-choice questions on Electrophilic substitution (Aromatic Hydrocarbons) for NEET Chemistry, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.
Practice thousands more NEET questions in the app →Q1. The nature of the electrophile determines the type of reaction. Which electrophile is usually used for the nitration of benzene?
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Correct answer: B — NO₂⁺
Nitration of benzene requires the electrophile NO₂⁺, which is generated from the reaction of nitric acid and sulfuric acid (nitrating mixture).
Q2. If a ring is substituted with a strongly deactivating group, the overall rate of electrophilic substitution on that ring will be:
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Correct answer: A — Decreased significantly
Deactivating groups decrease the overall electron density of the ring, making it less nucleophilic and therefore significantly slowing down the rate of electrophilic substitution.
Q3. Which of the following compounds is typically the most reactive towards electrophilic substitution among the benzene derivatives?
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Correct answer: C — Benzene
Benzene is the parent aromatic compound and serves as the baseline for electrophilic substitution.
Q4. Which of the following compounds is generally most reactive towards electrophilic substitution?
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Correct answer: D — Benzene
Benzene is the parent aromatic compound. While phenol is highly reactive, benzene serves as the baseline for simple electrophilic substitution reactions; it is the most readily substituted system among the basic forms.
Q5. Which type of reaction is characteristic of electrophilic substitution on benzene rings?
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Correct answer: A — Electrophilic Attack
Electrophilic substitution involves the attack of an electrophile (an electron-deficient species) onto the electron-rich aromatic ring.
Q6. The stability of the arenium ion intermediate formed during electrophilic substitution is directly related to which factor?
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Correct answer: B — resonance stabilization
The stability of the arenium ion intermediate is maximized when the positive charge is delocalized over the ring through resonance, which is the fundamental basis of aromatic stability.
Q7. The reaction of phenol with Br₂ in a non-aqueous solvent results in the formation of ortho- and para-substituted products. This is due to the high reactivity provided by the:
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Correct answer: D — Resonance effect
Phenol is highly activated by the -OH group, which donates electron density through resonance, thereby making the ring highly susceptible to electrophilic attack.
Q8. The ortho and para directing effect observed in the electrophilic substitution reactions of a benzene ring is primarily due to:
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Correct answer: A — Mesomeric effect (Resonance)
The ortho and para directing effects are governed by the stabilization of the intermediate arenium ion by the electron-donating nature (resonance effect) of the substituent groups, which facilitates the formation of more stable transition states.
Q9. Which of the following compounds is an example of a simple aromatic hydrocarbon?
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Correct answer: C — Toluene
Toluene (methylbenzene) is a simple aromatic hydrocarbon, derived from benzene by substituting a hydrogen atom with a methyl group. Phenol is a benzene derivative with an -OH group attached.
Q10. In the reaction of phenol with Br₂ in a non-aqueous solvent, the major product formed is:
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Correct answer: D — o-Dibromophenol
The hydroxyl group (OH) is a strongly activating and ortho/para-directing group. Since the reaction is carried out in a non-aqueous solvent (like CS₂ or CCl₄), the primary product formed is the vicinal dibromophenol, which strongly favors the ortho and para positions.
Q11. Which functional group is a deactivating group and a meta-director in electrophilic aromatic substitution reactions?
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Correct answer: A — -NO₂
The nitro group (-NO₂) is strongly electron-withdrawing via both inductive and resonance effects, making the ring deactivated towards EAS and directing incoming electrophiles meta.
Q12. The NO₂ group is a strongly deactivating group. Where will the incoming electrophile preferentially substitute benzene ring when the NO₂ group is present?
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Correct answer: D — meta
The nitro group (NO₂) is a deactivating group, and it withdraws electron density from the ring. It directs the incoming electrophile to the meta positions due to resonance stabilization of the intermediate formed at the meta positions.
Q13. The stability of the arenium ion (sigma complex) formed during electrophilic substitution is primarily determined by the presence of:
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Correct answer: A — Resonance stabilization
The stability of the intermediate carbocation (arenium ion) is maximized when resonance structures are possible, which is the hallmark of aromatic stabilization.
Q14. When a benzene ring undergoes electrophilic substitution, the resulting product exhibits which characteristic stability?
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Correct answer: D — higher resonance energy
The substitution reaction involves the loss of aromaticity, forming a resonance-stabilized carbocation intermediate (arenium ion). The stability gained by restoring aromaticity is greater than the energy required for substitution.
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