Chemistry Solids ETEA 2024
PMDC Verified Question 11 of 54
When a crystalline substance conducts current in one direction but not through other directions of the crystal, this property is:
A
Allotropy
B
Anisotropy
C
Isomorphism
D
Polymorphism
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Anisotropy
Concept:
Crystalline solids have highly ordered internal geometric arrangements, meaning the spacing between atoms often varies depending on the axis (x, y, or z) being observed.

Solution:
  • If a physical property—like electrical conductivity—changes in magnitude depending on the direction it is measured within the crystal, the phenomenon is termed anisotropy.
  • A classic example is graphite, which conducts electricity parallel to its internal carbon layers (due to delocalized electrons), but acts as an insulator perpendicular to them.


Why other options are incorrect:
  • A: Allotropy is when one element exists in multiple structural forms (e.g., carbon as diamond and graphite).
  • C: Isomorphism is when different compounds share the same crystal structure.
  • D: Polymorphism is when a single compound can crystallize in more than one structure.

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