Chemistry Transition Elements MDCAT 2011
PMDC Verified Question 66 of 68
Tick the correct statement
A
Chelates are more stable than ordinary complexes
B
Ordinary complexes are more stable than chelates
C
Monodentate ligand form chelate
D
Chelates have no ring structure
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Chelates are more stable than ordinary complexes
Concept:

A chelate is a cyclic complex formed when a multidentate ligand binds to a single central metal atom at two or more donor sites, creating a ring structure.

Solution:

  • Chelate Effect: Chelates are thermodynamically much more stable than similar complexes formed by monodentate ligands.


  • This is largely driven by entropy (\(\Delta S\)). When a multidentate ligand binds, it often displaces multiple monodentate ligands (like water), increasing the total number of free molecules in solution and thus increasing the system's disorder (entropy).


  • Therefore, statement A is correct.


Why other options are incorrect:

  • Option C: Monodentate ligands only bind to one site; they cannot form rings (chelates).


  • Option D: Chelates are defined by their ring structures.

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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