Chemistry Solids NUMS 2024
PMDC Verified Question 16 of 54
Iodine is a poor conductor of electricity because of:
A
Face centered cubic structure
B
Body centered cubic structure
C
Tetragonal structure
D
Hexagonal 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: Face centered cubic structure
Concept:
Solid iodine (\( \text{I}_2 \)) is a non-polar molecular solid. (Note: The original question stem phrasing is an artifact of the historical textbook's formatting, conflating conductivity with crystalline shape. We address the intended structural answer here.)

Solution:
  • Iodine is fundamentally a poor conductor of electricity because its valence electrons are localized in discrete, neutral \( \text{I}_2 \) covalent molecules, leaving no free electrons.
  • Regarding its solid-state structural geometry—which the options are querying—solid iodine crystallizes such that the \( \text{I}_2 \) molecules occupy the lattice points of a face-centered cubic (FCC) unit cell (according to this specific textbook curriculum).
  • Therefore, recognizing the structural characteristic highlighted by the textbook key, the face-centered cubic structure is the designated answer.


Why other options are incorrect:
  • B, C, D: Standard entry-level chemistry curricula for this region designate the solid iodine unit cell as face-centered cubic, making BCC, tetragonal, and hexagonal incorrect in this context.

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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