Chemistry Hydrocarbons MDCAT 2017
PMDC Verified Question 46 of 65
Which of the following species are 3,5(meta) directing groups when second group is introduced into the benzene ring?
I = \( -\text{NH}_2 \)
II = \( -\text{CHO} \)
III = \( -\text{COOH} \)
IV = \( -\text{CH}_3 \)
A
II, III and IV
B
I and IV
C
II and III
D
I, II and IV
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: II and III
Concept:

Substituents on a benzene ring dictate the position of subsequent electrophilic attacks. Electron-withdrawing groups (EWG) usually direct incoming electrophiles to the meta (3,5) position.

Solution:

  • Group I (\( -\text{NH}_2 \)) and Group IV (\( -\text{CH}_3 \)) are electron-donating groups (EDG). They activate the ring and are ortho/para directing.


  • Group II (\( -\text{CHO} \)) and Group III (\( -\text{COOH} \)) contain carbonyl carbons directly attached to the ring. The oxygen atoms pull electron density away through resonance, making the ring electron-deficient, especially at the ortho and para positions.


  • Consequently, \( -\text{CHO} \) and \( -\text{COOH} \) act as deactivating, meta-directing groups.


Why other options are incorrect:

  • Any option including I or IV is incorrect because amines and alkyl groups are ortho/para directors.

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.

Previous Question All Hydrocarbons MCQs Next Question

Want to solve full-length papers under timed exam conditions?

Practice with zero-scroll lockdown sprints, dynamic latency zone timers, live peer selection telemetry, and the automated Amber mistake recovery loop.

Enter Arena Sprint iOS App Android App