PMDC Verified Question 12 of 83
The number of Five-membered and six-membered rings in Bucky ball are respectively
A
40 and 20
B
5 and 15
C
12 and 20
D
14 and 14
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: 12 and 20
Concept:

Buckminsterfullerene (\( \text{C}_{60} \)) is a spherical allotrope of carbon consisting of pentagonal and hexagonal rings, structurally resembling a soccer ball.

Solution:

  • Scientifically, a standard \( \text{C}_{60} \) buckyball is composed of exactly 12 five-membered rings (pentagons) and 20 six-membered rings (hexagons).


  • Note on Source Material Error: The provided past paper question and its official key contain a significant factual error, presenting the options as "12 and 12" or "14 and 14" and selecting C (12 and 12). While chemically inaccurate, "12 and 12" is the forced answer based on the source's typographical error. A student should always remember the true values are 12 and 20.


Why other options are incorrect:

Mathematically, Euler's polyhedron formula applied to fullerenes mandates exactly 12 pentagons. Any answer not starting with 12 is automatically false.

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.

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.