Chemistry Stoichiometry MDCAT 2014
PMDC Verified Question 98 of 105
A polymer of simplest formula \( \text{CH}_2 \) has molar mass of \( 28000 \text{ g mol}^{-1} \). Its molecular formula will be:
A
100 times that of its empirical formula
B
500 times of its empirical formula
C
200 times that of its empirical formula
D
2000 times that of its empirical formula
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: 2000 times that of its empirical formula
Concept:

A polymer's molecular formula is an exact integer multiple (n) of its empirical (simplest) formula. This integer is found by dividing the total molar mass by the empirical formula mass.

Formula:

$$ n = \frac{\text{Molar Mass}}{\text{Empirical Formula Mass}} $$

Solution:

  • The simplest (empirical) formula is \( \text{CH}_2 \).


  • Empirical formula mass = \( 12 + (2 \times 1) = 14 \text{ g/mol} \).


  • Given total molar mass = \( 28,000 \text{ g/mol} \).


  • Calculate the multiplier: \( n = 28000 / 14 = 2000 \).


  • Thus, the molecular formula is 2000 times the empirical formula.


Why other options are incorrect:

  • 100 / 200 / 500 times: These result from incorrect division arithmetic or misunderstanding the molar mass of the repeating unit.

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 Stoichiometry 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