Chemistry Gases MDCAT 2013
PMDC Verified Question 62 of 65
There are four gases \( \text{H}_2 \), He, \( \text{N}_2 \) and \( \text{CO}_2 \) at 0°C. Which gas shows greater non-ideal behavior?
A
He
B
\( \text{H}_2 \)
C
\( \text{CO}_2 \)
D
\( \text{N}_2 \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: \( \text{CO}_2 \)
Concept:

Deviation from ideal gas behavior is caused by two main factors: the significant actual volume of gas molecules and the presence of intermolecular forces of attraction. Larger and more polarizable molecules deviate more.

Solution:

  • Among the given options, \( \text{CO}_2 \) is a multi-atomic molecule with the largest molar mass (44 g/mol) and the largest molecular size.


  • Due to its larger size and electron cloud, \( \text{CO}_2 \) has stronger London dispersion forces compared to the smaller diatomic or monatomic gases.


  • The order of non-ideality is: He < \( \text{H}_2 \) < \( \text{N}_2 \) < \( \text{CO}_2 \). Therefore, \( \text{CO}_2 \) shows the greatest deviation.


Why other options are incorrect:

  • Options A & B: Helium and Hydrogen are tiny, extremely light gases with negligible intermolecular forces, making them behave closest to ideal gases.
  • Option D: Nitrogen is larger than He and \( \text{H}_2 \), but significantly smaller and less polarizable than \( \text{CO}_2 \).

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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