MCQ on electrophilic reaction

MCQs – Electrophilic Reactions (20 Practice Questions)

Q1. Electrophilic addition is generally observed in?

Answer: A. Electrophilic addition is typical for π-bond containing compounds like alkenes and alkynes.

Q2. In the first step of electrophilic addition, the electrophile attacks?

Answer: A. The electrophile attacks the electron-rich π-bond to form a carbocation intermediate.

Q3. Which is a common example of electrophilic substitution reaction?

Answer: A. Nitration, halogenation, sulphonation of benzene are classic electrophilic substitution reactions.

Q4. In Markovnikov’s rule, the electrophile attaches to the carbon having?

Answer: A. According to Markovnikov’s rule, the electrophile attaches to the carbon with more hydrogens, stabilizing the carbocation.

Q5. Anti-Markovnikov addition occurs in the presence of?

Answer: B. Peroxides cause free-radical mechanism leading to anti-Markovnikov addition (Kharasch effect).

Q6. Which intermediate is formed in most electrophilic addition reactions?

Answer: A. Carbocations are key intermediates in electrophilic addition.

Q7. Which of the following is an electrophile?

Answer: A. H⁺ ion is electron-deficient and acts as an electrophile.

Q8. Which reaction is an example of electrophilic substitution?

Answer: A. Bromination of benzene involves electrophilic substitution.

Q9. Which of the following stabilizes a carbocation formed in electrophilic addition?

Answer: A. Hyperconjugation stabilizes carbocations.

Q10. In the nitration of benzene, the attacking electrophile is?

Answer: A. The nitronium ion (NO₂⁺) is the actual electrophile.

Q11. Which condition favors electrophilic aromatic substitution?

Answer: A. Electron donating groups activate the benzene ring.

Q12. Which is NOT an electrophilic substitution reaction?

Answer: C. Aldol condensation is nucleophilic in nature.

Q13. The catalyst used in Friedel-Crafts alkylation is?

Answer: A. AlCl₃ is used as a Lewis acid catalyst.

Q14. Which species attacks in the sulphonation of benzene?

Answer: A. SO₃ acts as the electrophile.

Q15. Electrophilic addition to alkynes gives mostly?

Answer: A. Alkynes react with electrophiles giving vinyl carbocations.

Q16. In halogenation of benzene, the role of FeCl₃ is?

Answer: A. FeCl₃ helps generate Cl⁺ electrophile.

Q17. Which intermediate is common in EAS reactions?

Answer: A. Arenium ion (sigma complex) is the intermediate.

Q18. Which of the following is an electron donating group in benzene?

Answer: A. -OH donates electron by resonance, activating the ring.

Q19. Which of the following undergoes electrophilic substitution fastest?

Answer: A. Phenol is highly activated towards EAS due to -OH group.

Q20. Which directing group is meta-directing in EAS?

Answer: A. -NO₂ is electron-withdrawing and meta-directing.