Which statement is true about a sample of gas containing molecules of different masses?

a) More-massive gas molecules in the sample have greater rms speed than less-massive ones.


b) More-massive gas molecules in the sample have lesser rms speed than less-massive ones.


c) The rms speed depends only on temperature, and so all types of particles in the sample have the same rms speed.Which statement is true about a sample of gas containing molecules of different masses?
bWhich statement is true about a sample of gas containing molecules of different masses?
Answer b.


Definition of RMS speed is





RMSspeed= sqrt(3RT/M), where T is temperature and M is molar mass of the molecules. So the speed depends on both temperature and mass. Since M is in denominator, the larger it (M) is the slower the speed.