question_answer

The ratio of vapour densities of two gases at the same temperature is 8:9. Compare the r. m. s. velocities of their molecules.              

Answer:

                \[\frac{{{({{\upsilon }_{rms}})}_{1}}}{{{({{\upsilon }_{rms}})}_{2}}}=\sqrt{\frac{{{M}_{2}}}{{{M}_{1}}}}\]                 \[=\sqrt{\frac{{{\rho }_{2}}}{{{\rho }_{1}}}}=\sqrt{\frac{9}{8}}=\mathbf{3:2}\sqrt{\mathbf{2}}\mathbf{.}\]