Chemistry Hydrocarbons PMDC 2020
PMDC Verified Question 22 of 65
When \( \text{CH}_3 \) is attached with the benzene ring, it makes the ring:
A
Good electrophile
B
Resonance hybrid
C
Extraordinary stable
D
Good nucleophile
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Good nucleophile
Concept:

Alkyl groups are electron-donating. A higher electron density on an aromatic ring enhances its ability to seek out and attack positive centers (electrophiles).

Solution:

  • The methyl group (\( -\text{CH}_3 \)) pushes electrons into the benzene ring via the positive inductive effect (+I) and hyperconjugation.


  • This localized increase in pi-electron density makes the ring highly rich in negative charge.


  • An electron-rich species that attacks electrophiles is by definition a good nucleophile. Thus, toluene is a stronger nucleophile than bare benzene.


Why other options are incorrect:

  • Electrophiles seek electrons; the electron-rich toluene ring repels other electrons, meaning it does not act as an electrophile.


  • The ring is already a resonance hybrid; attaching \( \text{CH}_3 \) doesn't initiate that property.


  • It actually becomes more reactive (less kinetically stable) toward substitution than plain benzene.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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