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QJEEM24Ph3018: JEE Main 2024 Physics - Class 11 JEEM24Ph3018 Solution: Given below are two statements : Statement (I) : The mean free…

Given below are two statements :

Statement (I) : The mean free path of gas molecules is inversely proportional to square of molecular diameter.

Statement (II) : Average kinetic energy of gas molecules is directly proportional to absolute temperature of gas.

In the light of the above statements, choose the correct answer from the options given below :

Multiple Choice Options

  • A Statement I is false but Statement II is true
  • B Both Statement I and Statement II are true
  • C Statement I is true but Statement II is false
  • D Both Statement I and Statement II are false

Step-by-Step Verified Solution

Let's analyze the given statements one by one in detail:

Statement (I): The mean free path of gas molecules is inversely proportional to the square of molecular diameter.

The mean free path ( λ\lambda ) of gas molecules is the average distance a molecule travels before colliding with another molecule. The formula for the mean free path in terms of molecular diameter ( dd ) is given by:

λ=kBT2πd2P\lambda = \frac{k_B T}{\sqrt{2} \pi d^2 P}

Here, kBk_B is the Boltzmann constant, TT is the temperature, and PP is the pressure. From this equation, it is evident that the mean free path ( λ\lambda ) is inversely proportional to the square of the molecular diameter ( d2d^2 ). Hence, Statement I is true.

Statement (II): Average kinetic energy of gas molecules is directly proportional to absolute temperature of gas.

The average kinetic energy ( EavgE_{\text{avg}} ) of gas molecules is given by:

Eavg=32kBTE_{\text{avg}} = \frac{3}{2} k_B T

where kBk_B is the Boltzmann constant and TT is the absolute temperature. This shows that the average kinetic energy is directly proportional to the absolute temperature of the gas. Hence, Statement II is true.

Considering the analysis above, the correct answer is:

Option B
Both Statement I and Statement II are true

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