How should the condition be changed to prevent the value of a given gas from expanding when its mass is increased? · Gases MDCAT Past Paper MCQ

Chemistry Gases NUMS 2022

PMDC Verified Question 45 of 65

How should the condition be changed to prevent the value of a given gas from expanding when its mass is increased?

Temperature is lowered & pressure is increased

Temperature is increased & pressure is lowered

Temperature & pressure both are lowered

Temperature & pressure both are increased

Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:

Option A: Temperature is lowered & pressure is increased

Concept:

We need to counteract an expansion in volume. By analyzing the ideal gas law ($ PV = nRT $), we can see how manipulating temperature and pressure affects volume.

Formula:

$$ V = \frac{nRT}{P} $$

Solution:

When mass (and thus moles, $ n $) is increased, Volume ($ V $) naturally wants to increase to accommodate the extra particles.

To prevent this expansion (keep $ V $ constant or force it down), we must look at the remaining variables: Temperature ($ T $) and Pressure ($ P $).

Since $ V \propto T $, lowering the temperature will decrease the volume.

Since $ V \propto \frac{1}{P} $, increasing the pressure will compress the gas, also decreasing the volume.

Applying both simultaneously (lowering temperature AND increasing pressure) strongly counteracts the expansion caused by adding mass.

Why other options are incorrect:

Option B: Both actions would cause massive expansion, worsening the issue.
Options C & D: These combinations have opposing effects on volume, making them less effective or completely ineffective at strictly preventing expansion.

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 Gases 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