Chemistry Gases NUMS 2024
PMDC Verified Question 17 of 65
The relationship between the absolute temperature and the velocities of the gas molecules is given by:
A
\( C_{rms} = \sqrt{3RT/M} \)
B
\( PV = nRT \)
C
\( V = \sqrt{2E_k/m} \)
D
\( PV = 1/3 mN\overline{c}^2 \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: \( C_{rms} = \sqrt{3RT/M} \)
Concept:

The Kinetic Molecular Theory relates the macroscopic absolute temperature of a gas directly to the microscopic average speeds of its constituent molecules via the Root Mean Square (RMS) velocity.

Formula:

$$ C_{rms} = \sqrt{\frac{3RT}{M}} $$

Solution:

  • In this equation, \( C_{rms} \) is the root mean square velocity, \( R \) is the universal gas constant, \( T \) is the absolute temperature in Kelvin, and \( M \) is the molar mass.


  • This explicit formula defines how molecular velocity is directly proportional to the square root of the absolute temperature (\( C_{rms} \propto \sqrt{T} \)).


Why other options are incorrect:

  • Option B: The ideal gas law relates Pressure, Volume, and Temperature, but does not explicitly calculate molecular velocity.
  • Option C: While mathematically true for classical kinetic energy, it does not directly incorporate the macroscopic "Absolute Temperature" (T) as requested by the prompt.
  • Option D: The kinetic gas equation relates Pressure and Volume to mean square velocity, but does not explicitly contain Temperature (T).

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