Assertion : Mean free path of a gas molecule varies inversely as density of the gas.
Reason : Mean free path varies inversely as pressure of the gas.

Options

A. If both assertion and reason are true and the reason is the correct explanation of the assertion
B. If both assertion and reason are true but reason is not the correct explanation of the assertion
C. If assertion is true but reason is false.
D. If the assertion and reason both are false.

Answer

A

Explanation

The mean free path of a gas molecule is the average distance between two successive collisions. It is represented by `gamma` .
`lambda = 1/sqrt2 (kT)/(pi sigma^2 P ) and lambda = m/(sqrt2. pisigma^2 d)`
Here, `sigma = 0` diameter of molecule and
k = Boltzmann.s constant.
`rArr lambda prop 1 //d , lambda prop T and lambda prop 1 //P`.
Hence, mean free path varies inversely as density of the gas.
It can be easily proved that the mean free path varies directly as the temperature and inversely as the pressure of the gas.