Question

The $RMS$ velocity of gas molecules at $NTP$ cannot be calculated from which one of the following formula?

• A. $\sqrt{\frac{3P}{d}}$
• B. $\sqrt{\frac{3PV}{M}}$
• C. $\sqrt{\frac{3RT}{M}}$
• D. $\sqrt{\frac{3RT}{d}}$

Answer 1

Answer: (D)

$\sqrt{\frac{3RT}{d}}$

The $RMS$ velocity of gas molecules at $NTP$ cannot be calculated from $\sqrt{\frac{3RT}{d}}$.
It can be calculated from the formulas $\sqrt{\frac{3P}{d}}$, $\sqrt{\frac{3PV}{M}}$ and $\sqrt{\frac{3RT}{M}}$.
Here, $R$ is the ideal gas constant, $T$ is the temperature, $M$ is the molar mass, $P$ is the pressure, $V$ is the volume and $d$ is the density of the gas.