NEETPhysicsKinetic Theory of Gases
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): If the temperature of a given mass of gas in a closed rigid vessel is increased, its mean free path remains constant. Reason (R): The mean free path of a gas is inversely proportional to its absolute temperature at constant volume. In the light of the above statements, choose the most appropriate a
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is not correct
- D(A) is not correct but (R) is correct
Correct answer
C. (A) is correct but (R) is not correct
Step-by-step solution
The mean free path of gas molecules is given by = 1 2 d^2 n , where n is the number density ( n = N V ). In a closed rigid vessel, both the total number of molecules ( N ) and the volume ( V ) remain constant. Therefore, the number density ( n ) is constant. Since depends only on the molecular diameter and number density, it remains constant even if the temperature is increased. Thus, Assertion (A) is correct. Reason (R) is incorrect because the mean free path is independent of temperature as long as the volume (an