Question

Three closed vessels A, B and C are at the same temperature T and contain gases which obey the Maxwellian distribution of velocities. Vessel A contains only $O_{2}$, B only $N_{2}$ and C a mixture of equal quantities of $O_{2}$and$N_{2}$. If the average speed of the $O_{2}$ molecules in vessel A is $V_{1}$, that of the $N_{2}$ molecules in vessel B is $V_{2}$, the average speed of the $O_{2}$ molecules in vessel C is (where M is the mass of an oxygen molecule)

• A. $(V_{1} + V_{2})/2$
• B. $V_{1}$
• C. $(V_{1}V_{2})^{1/2}$
• D. $\sqrt{3kT/M}$

Answer 1

Answer: (B)

$V_{1}$

Answer 2

Average speed of gas molecule $v_{av} = \sqrt{\frac{8kT}{\pi m}}$. It depends on temperature and molecular mass. So the average speed of oxygen will be same in vessel A and vessel C and that is equal to $V_{1}$.