Chemistry Hydrocarbons NUMS 2019
PMDC Verified Question 30 of 65
Which of the following compound react slower than benzene in electrophilic substitution reaction
A
Phenol
B
Aniline
C
Nitrobenzene
D
Toulene
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Nitrobenzene
Concept:

The reactivity of substituted benzenes depends on whether the attached group pushes electrons into the ring (activating) or pulls electrons out (deactivating).

Solution:

  • Electrophilic substitution requires an electron-rich aromatic ring to attack a positive electrophile.


  • The nitro group (\( -\text{NO}_2 \)) is a very strong electron-withdrawing group via both induction and resonance.


  • It dramatically drains electron density from the pi system, making the ring heavily electron-deficient.


  • Therefore, Nitrobenzene is strongly deactivated and reacts much slower than unsubstituted benzene.


Why other options are incorrect:

  • Phenol (\( -\text{OH} \)), Aniline (\( -\text{NH}_2 \)), and Toluene (\( -\text{CH}_3 \)) all contain electron-donating groups. They increase the ring's electron density, making them react faster than 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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