Chemistry - Ideal Gas Question with Solution | TestHub

The average velocity formula $U_{av}=\sqrt{\frac{8RT}{\pi M}}$ is correct.

The RMS velocity formula does not contain $\pi$, so option (b) is incorrect.

Also, $P=\rho RT$ and $U_{av}=0.816U_{rms}$ are standard relations.

Hence, the correct options are (a), (c), (d).